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Ministry of Energy Mines and Responsible for Core Review

A - Organic

(Example Deposits)

BC Profile # Deposit Type Approximate Synonyms USGS Model #
A01 Peat - - - -
A02 Lignite Brown coal - -
A03 Sub-bituminous coal Thermal coal, Black lignite - -
A04 Bituminous coal Coking coal, Thermal coal - -
A05 Anthracite Stone coal - -
 

PEAT


A01
by Z.D. Hora
Retired, British Columbia Geological Survey, Victoria, B.C., Canada
Hora, Z.D. (2007): "Peat", in Selected British Columbia Mineral Deposit Profiles.

 

IDENTIFICATION

 

SYNONYMS: Sphagnum moss, horticultural peat, peat bog, humus peat, fen peatland, muskeg, organics, non-permafrost bogs.

 

COMMODITIES (BYPRODUCTS): horticultural peat, pollution control peat, filtration peat, energy (fuel) peat.

 

EXAMPLES (British Columbia – Canada/International):  Burns bog, Pitt River bog, Fort Nelson Lowland peats, Peace River Lowland peats; Alberta, Quebec, New Brunswick, Ireland, Germany, Netherlands, Finland, Russia.

 

GEOLOGICAL CHARACTERISTICS

 

CAPSULE DESCRIPTION: Peatlands are classified into two categories: bogs and fens. Bogs receive their water only from precipitation and have low water flow, whereas fens are affected by mineral-rich ground and/or surface waters. Bogs have shallow water tables (generally about 50 cm below the peat surface). Land surfaces are generally poorly drained, level and may be slightly raised above the surrounding area.  They may be treed. Peat bogs are acidic (pH below 4.5) and dominated by species of Sphagnum, feather moss, lichens, and ericaceous shrubs. Fens also have water tables at or just above surface and land surfaces are gently sloping to almost level. The vegetation is dominated by sedges, reeds, brown mosses, Sphagnum moss and ericaceous shrubs.

 

TECTONIC SETTING: Unimportant. Peat deposit formation is dependent largely on climatic and terrain conditions.

 

DEPOSITIONAL ENVIRONMENT / GEOLOGICAL SETTING: Peat deposits occur in topographic depressions often caused by melting ice in glacial tills or flat plains, usually overlying relatively impermeable materials, such as glaciolacustrine sediments and clay-rich tills. They are common in areas with poorly organized drainage systems and can occur locally on gentle slopes where precipitation is high and evaporation low. Stable regional water tables, anaerobic conditions and decreased nutrient availability are important for peat development. These factors lead to a substantial decrease in decomposition rates and a net accumulation of peat.

 

AGE OF MINERALIZATION: In Canada, most peatlands have formed since the end of the last ice age, about 13 000 to 10 000 years BP. Significant peat formation typically occurred after large areas that had been inundated by glacial lakes had drained, or after oceanic and lacustrine areas were uplifted by the postglacial isostatic rebound of the land.  In British Columbia, peatland development was slow until after the warm and dry mid-Holocene period terminated around 4000 to 5000 years ago.

 

HOST/ASSOCIATED ROCK TYPES: Peatland. Associated sediments are marl deposits; organic-rich sediments; gyjatta; diatomaceous earth; overlie a variety of surficial deposits including clay till, glaciolacustrine and glaciofluvial sediments, ice contact deposits, and alluvium.

 

DEPOSIT FORM: Commonly, surface layers of weakly decomposed Sphagnum moss, up to several metres thick, are underlain by well decomposed sedge and/or Sphagnum peat, typically a few metres thick. In most deposits, the total depth of organic material is less than 10 metres. Some coalescing peat bogs can cover areas of several thousands of hectares in size.

 

TEXTURE/STRUCTURE: Peat is a soft, fibrous material with moisture content in its natural state of over 90%. Sphagnum moss has a high water-holding capacity (it can hold 15 to 20 times its weight in water), high cation exchange capacity, high pore space, low bulk density and high permeability.

 

ORE MINERALOGY (Principal and subordinate): Sphagnum peat, sedge peat, shrub and root fragments. There are about 85 species of Sphagnum known in North America.

 

GANGUE MINERALOGY (Principal and subordinate): Surface vegetation, stumps, sediment or marl interbeds.

 

ALTERATION MINERALOGY: Well decomposed sedge and/or brown peat moss (suitable as fuel peat).

 

WEATHERING: Decomposition of the organic matter is required to produce peat; various degrees of decomposition are preferred depending on the final product type.

 

ORE CONTROLS: The formation and localization of peat is a dynamic, continuous process, influenced by a number of factors, including climate and topography. The best quality Sphagnum peat develops as a slightly elevated dome that is raised above the water table. Boreal regions are the host of most peatlands in Canada.

 

GENETIC MODEL: Peatland formation is largely dependent on climatic and hydrogeologic factors. Peat accumulates in areas where water remains standing throughout the year due to a positive water balance. Organic material derived from vegetation builds up when the rate of accumulation is greater than the rate of decomposition. This balance is usually achieved in areas of temperate climate. Under higher temperatures, such as those in the tropics, vegetation growth is favoured but the rate of decomposition is rapid so that the accumulation of organic matter is low. Stabilized water levels, anaerobic conditions and decreased nutrient availability lead to a substantial decrease in decomposition rates, which results in the development of peat accumulating ecosystems. The rate of accumulation can be as much as 1-2 mm/year, but generally may average from 0.6-0.7 mm/ year in many Canadian peatlands.

 

ASSOCIATED DEPOSIT TYPES: Marl (B11), gyjatta, lacustrine diatomite (F06), glacial, glaciolacustrine and glaciofluvial sand and gravel deposits.

 

EXPLORATION GUIDES

 

GEOCHEMICAL SIGNATURE: not applicable.

 

GEOPHYSICAL SIGNATURE: Ground penetrating radar has been used successfully in Sweden and Alaska to obtain three-dimensional pictures of peat bogs.

 

OTHER EXPLORATION GUIDES: Organic deposits occur in topographic depressions, along drainage ways, particularly on nearly level areas with poor drainage, and also on some slopes where precipitation is high and evaporation is low, such as northern coastal areas in BC. Air photo interpretation and remote sensing can identify peat landforms on the surface but ground truthing is needed to establish the subsurface nature of the deposit. Ground investigations include evaluations of surface vegetation, depth of the peat, Von Post degree of decomposition, size of the deposit, pH of the peat, botanical composition and identification of moss species present.

 

ECONOMIC FACTORS

 

TYPICAL GRADE AND TONNAGE: Published data on individual deposits are rare, but according to Canadian Sphagnum Peat Moss Association, peat quality must meet market requirements regarding composition – the preferred composition is a weakly decomposed Sphagnum peat with a minimum content of shrubs and roots. The majority of producing sites have Sphagnum layers 1 to 4 metres thick. An aerial extent of 50 hectares is usually required, but some bogs may cover several thousands of hectares. 

 

ECONOMIC LIMITATIONS: In North America, a thickness of 2 metres and an area of 50 hectares is generally considered the minimum for economic viability. The site must have good potential to build an enhanced drainage system, be close to infrastructure (particularly road access), and have a low-density tree cover. Local climate should have dry periods without much rain during the main harvest period.

 

END USES: Most of the peat is sold as compressed bales for use in the horticultural and nursery industries; some is used in soil mixes and other greenhouse and gardening products. Peat is important in environmental clean-up operations as absorbent and filtration media. Globally, about 13% is used as a fuel (e.g., in Russia, Finland, Ireland and Germany).

 

IMPORTANCE: In Canada, peatlands comprise over 12% of the land surface area, although much of this area is not viable for peat production. Less than 0.02% of the surface area of Canada has been used for peat production. Canadian peat production averages 700 000 to 800 000 tonnes annually with a value over $90 million/year. The main producing provinces are New Brunswick and Quebec, with Alberta ranked third. British Columbia’s peat production was from the Fraser delta, which was mined out in the 1970s. Peat in Canada is produced from 45 deposit areas in 8 provinces; most of the production is exported to the USA and overseas, particularly Japan. Because of a steady growth of peat in Canada's boreal regions, over 50 million tonnes of peat accumulates every year in Canada compared to 700 000 to 800 000 tonnes annually produced. Reclamation and restoration of mined-out areas can be accomplished by impeding the drainage. Experience from eastern Canada indicates that in 5 to 20 years (depending on local circumstances) the mined-out areas can be restored into ecologically balanced systems.

 

REFERENCES

 

Buteau, P. (2001): Peat in Canada; in Dunlop, S. and Simandl, G., Editors, Industrial Minerals in Canada, Canadian Institute of Mining, Metallurgy and Petroleum, Special Volume 53, pages 275–284.

Hood, G. (2001): The Canadian Peat Moss Industry; in Dunlop. S. and Simandl, G., Editors, Industrial Minerals in Canada, Canadian Institute of Mining, Metallurgy and Petroleum, Special Volume 53, pages 285–290.

Keys, D. (1992): Canadian Peat Harvesting and the Environment, Issues Paper, Number 1992–3, North American Wetlands Conservation Council (Canada), 29 pages.

Keys, D. (1982): The Assessment of New Brunswick Peatlands, Paper at the 84th Annual General Meeting, The Canadian Institute of Mining and Metallurgy, 22 pages.

Maynard, D.E. (1988): Peatland Inventory of British Columbia, Open File 1988-33, BC Ministry of Energy, Mines and Petroleum Resources, 73 pages.

Monenco Ontario Limited (1981): Evaluation of the Potential of Peat in Ontario, Occasional Paper No.7, Ministry of Natural Resources Ontario, 193 pages.

Thibault, J.J. (1993): The Development of the Canadian Peat Industry, Paper presented at the Newfoundland Peat Opportunity Conference, 27 pages.

Van Ryswyk, A.L. and Broersma, K. (1992): Agriculture Use and Extent of British Columbia Wetlands, Technical Bulletin 1992–3E, Agriculture Canada, 130 pages.

Vitt, D.H. (1994): An overview of factors that influence the development of Canadian peatlands, Memoirs of the Entomological Society of Canada, Volume 169, pages 7–20.

Vitt, D.H., Halsey, L.A. and Zoltai, S.C. (1994): The bog landforms of continental Canada in relation to climate and permafrost patterns, Arctic and Alpine Research, Volume 26, pages 1–13.

 

LIGNITE

A02
by Barry Ryan
British Columbia Geological Survey


Ryan, Barry (1995): Lignite, in Selected British Columbia Mineral Deposit Profiles, Volume 1 - Metallics and Coal, Lefebure, D.V. and Ray, G.E., Editors, British Columbia Ministry of Employment and Investment, Open File 1995-20, pages 5-7.

 

IDENTIFICATION

 

SYNONYM: Brown coal.

 

COMMODITIES (BYPRODUCTS): Coal, coal liquids, (tar, gas, leonardite).

 

EXAMPLES (British Columbia - Canada/International): Hat Creek (092INW047); Skonun, Queen Charlotte Islands; Coal River (mapsheet 094M10W); Estevan (Saskatchewan); Texas (USA).

 

GEOLOGICAL CHARACTERISTICS

 

CAPSULE DESCRIPTION: Seams of brown to black coal hosted by clastic sedimentary rocks. It can still contain some imprints of the original vegetation. Wet and dense with a dull lustre. Slacks (disintegrates) on exposure to air.

 

TECTONIC SETTINGS: Stable continental basins; shelves on the trailing edge of continents; foreland (molasse) basins; back-arc basins; fault blocks, often associated with strike-slip movement to limit sediment influx.

 

DEPOSITIONAL ENVIRONMENT / GEOLOGICAL SETTING: An area of slow sedimentation, in fresh water, with few or no marine incursions. Delta; shoreline swamp; raised swamp; lake; floating vegetation mats.

 

AGE OF MINERALIZATION: Quaternary; Tertiary; occasionally older.

 

ASSOCIATED ROCK TYPES: Sedimentary rocks exhibiting evidence of fresh and or shallow water deposition; carbonaceous mudstones; siltstones and sandstones, often with cross-stratification and other sedimentary structures of shallow water origin.

 

DEPOSIT FORM: Lignite seams generally conform with regional bedding; sometimes seams are deposited in areas of local subsidence such as fault-controlled blocks or sink holes in karst topography, in which case deposits may be lens shaped. Occasionally seams can be thickened/deformed by surface slump, glacial drift or faulting. Seams may pinch out or split on the regional scale.

 

TEXTURE/STRUCTURE: Lignite retains a dull matted appearance and is composed mainly of the lithotype huminite. It is banded and jointed. Footwall sediments are often penetrated by roots or weathered to clay (seatearth).

 

COAL SEAMS / ASSOCIATED MINERAL MATTER: Lignite is defined as coal with an Rmax value of less than 0.4 %. In outcrop it contains between 30 to 40 % moisture. It usually contains a high percentage of the maceral vitrinite and lower percentages of fusinite and liptinite. Mineral matter occurs in the lignite seams as bands, as finely intermixed material of authogenic or detrital origin (inherent mineral matter) and as secondary material deposited in fractures and open spaces. Inherent mineral matter includes pyrite, siderite and kaolinite. It may be dissimilar to that of the surrounding rocks.

 

WEATHERING: Weathering of lignite reduces the calorific value by oxidizing the carbon- hydrogen complexes. Minerals such as pyrite oxidize to sulphates. Secondary carbonates are formed.

 

ORE CONTROLS: The regional geometry of coal seams is controlled by sedimentary features such as extent of the delta, trend of the shoreline, and trend of sand-filled river channels. Subsequent deformation, such as faulting and folding, is important for higher rank coals.

 

ASSOCIATED DEPOSIT TYPES: Peat (A01), sub-bituminous coal (A03), paleoplacers (C04).

 

COMMENTS: Lignite has the lowest rank of all classes of coal (Rmax less than 0.4 %).

 

EXPLORATION GUIDES

 

GEOCHEMICAL SIGNATURE: Geochemistry is generally not used as a prospecting tool for lignite.

 

GEOPHYSICAL SIGNATURE: Lignite has a low density. Resistivity is variable but can be low for lignite. Surface geophysical techniques include direct-current profiling, refraction and reflection seismic and gravity. Subsurface or bore- hole techniques include gamma logs, neutron logs, gamma-gamma density logs, sonic logs, resistivity logs and caliper logs.

 

OTHER EXPLORATION GUIDES: Presence of: a down-slope coal bloom; nonmarine sediments; coal spar in the sediments; small oily seeps. Presence of lignite seams can also be detected by methane escaping through the surrounding sediments and burn zones where the lignite outcrop has burnt, baking the surrounding sediments.

 

ECONOMIC FACTORS

 

TYPICAL GRADE AND TONNAGE: The heat value of lignite is low. Gross heating value on a moist ash-free basis is 15 to 20 MJ/kg. Net useable heat will be lower because of the high moisture content and included mineral matter. Mine reserves range from tens to hundreds of million tonnes.

 

ECONOMIC LIMITATIONS: Lignite is a bulk commodity which is expensive to transport. The low heating value and tendency for spontaneous combustion usually restrict lignite to local uses. The ratio of tonnage to useable heat is low so that there is a large amount of waste material generated.

 

END USES: Steam generation in turbines for electrical generation. Feed for liquefaction and gasification.

 

IMPORTANCE: Major source of fuel used for local electrical power generation. Approximately 10 to 20 Mt of lignite per year are required to support 1 MW of power generation capability.

 

REFERENCES

 

Armstrong, W.M., Fyles, J.T., Guelke, C.B., Macgregor, E.R., Peel, A.L., Tompson, A.R. and Warren, I.H. (1976):  Coal in British Columbia, A Technical Appraisal; B.C. Ministry of Energy, Mines and Petroleum Resources, Coal Task Force, 241 pages.
Cope, J.H.R., Duckworth, N.A., Duncan, S.V., Holtom, J.E.B., Leask, A.L., McDonald, K.A. and Woodman, S.P. (1983): Concise Guide to the World Coalfields; compiled by Data Bank Service, World Coal Resources and Reserves, IEA Coal Research.

Matheson, A. (1986): Coal in British Columbia; B.C. Ministry of Energy, Mines and Petroleum Resources, Paper 1986-3, 169 pages.

Smith, G.G. (1989): Coal Resources in Canada; Geological Survey of Canada, Paper 1989-4, 146 pages.

 
 

SUB-BITUMINOUS COAL

A03
by Barry Ryan
British Columbia Geological Survey
 

Ryan, Barry (1995): Sub-Bituminous Coal, in Selected British Columbia Mineral Deposit Profiles, Volume 1 - Metallics and Coal, Lefebure, D.V. and Ray, G.E., Editors, British Columbia Ministry of Employment and Investment, Open File 1995-20, pages 9-11.

 

IDENTIFICATION

 

SYNONYMS: Steam coal, thermal coal, black lignite.

 

COMMODITIES (BYPRODUCTS): Coal, coal liquids, (tar, gas).

 

EXAMPLES (British Columbia - Canada/International): Princeton (092HSE089), Tulameen (092HSE209), Quesnel (093B 036), Tuya River (104J 044); Whitewood and Highvale mines (Alberta, Canada), Powder River Basin (USA).

 

GEOLOGICAL CHARACTERISTICS

 

CAPSULE DESCRIPTION: Seams of black to brown coal hosted by clastic sedimentary rocks. The coal is banded dull and bright. Generally hard, sometimes the texture of the original vegetation is partially preserved.

 

TECTONIC SETTINGS: Stable continental basins; shelves on the trailing edge of continents; foreland (molasse) basins; back-arc basins.

 

DEPOSITIONAL ENVIRONMENT / GEOLOGICAL SETTING: An area of slow sedimentation in fresh water with few or no marine incursions. Can be produced by fault blocks associated with strike-slip movement to limit sediment influx. Delta; shoreline swamp; raised swamp; lake; floating vegetation mats.

 

AGE OF MINERALIZATION: Often Tertiary but can be older.

 

HOST/ASSOCIATED ROCK TYPES: Sedimentary rocks exhibiting evidence of non-marine deposition. Carbonaceous mudstones, siltstones and sandstones are the most common, often with cross-stratification and other sedimentary structures formed in shallow water.

 

DEPOSIT FORM: Coal seams generally conform with regional bedding; sometimes seams are deposited in areas of local subsidence, such as fault-controlled blocks or sink holes in karst topography, in which case deposits may be lens shaped. Occasionally seams can be thickened/deformed by surface slump, glacial drift or faulting. Seams may pinch out or split on a local or regional scale.

 

TEXTURE/STRUCTURE: Sub-bituminous coal is usually composed mostly of clarain and vitrain. Footwall sediments are often penetrated by roots or weathered to clay (seatearth).

 

COAL SEAMS/ASSOCIATED MINERAL MATTER: Sub-bituminous coal has Rmax values in the range of 0.4 to 0.6 %. In outcrop it can contain up to 30 % moisture. It usually contains a high proportion of vitrinite and lesser amounts of fusinite and liptinite. Mineral matter is in the coal as rock bands, as finely intermixed material of authogenic or detrital origin (inherent mineral matter) and as secondary material deposited in fractures and open spaces. Inherent mineral matter includes pyrite, siderite and kaolinite.

 

WEATHERING: Weathering of sub-bituminous coal reduces the calorific value by oxidizing the carbon-hydrogen complexes. Minerals in the mineral matter will also oxidize. Pyrite oxidizes to sulphates. Secondary carbonates are formed.

 

ORE CONTROLS: The regional geometry of the seam/seams is controlled by sedimentary features, such as the extent of the delta, trend of the shoreline, and trend of sand-filled river channels. Deformation (faulting and folding) is important in some deposits.

 

ASSOCIATED DEPOSIT TYPES: Lignite (A02); bituminous coal (A04), Shale-hosted Ni-Zn-Mo- PGE (E16), Phosphate - upwelling type (F07).

 

EXPLORATION GUIDES

 

GEOCHEMICAL SIGNATURE: Geochemistry is generally not used as a prospecting tool for coal.

 

GEOPHYSICAL SIGNATURE: Coal has a low density. Resistivity is variable to high. Surface techniques include direct-current profiling, refraction and reflection seismic, and gravity. Subsurface or bore-hole techniques include gamma logs, neutron logs, gamma-gamma density logs, sonic logs, resistivity logs and caliper logs.

 

OTHER EXPLORATION GUIDES: Presence of: a down-slope coal bloom; coal spar; small oily seeps or methane escaping through the surrounding sediments. Zones where the coal outcrops have ignited and burnt to some depth underground.

 

ECONOMIC FACTORS

 

TYPICAL GRADE AND TONNAGE: Gross heating value on an ash-free moist basis is 20 to 27 MJ/kg. Net useable heat will be lower because of the high moisture content and the presence of ash. Mine reserves range up to hundreds of millions of tonnes. The sub-bituminous coal resources of B.C. Tertiary coal basins commonly range up to 200 Mt (Hat Creek exceptional with 1000 Mt).

 

ECONOMIC LIMITATIONS: Coal is a bulk commodity which is expensive to transport. The moderate heating value and tendency for spontaneous combustion means that sub- bituminous coal is usually used locally for electrical power generation. The ratio of tonnage to useable heat is low so that there is a larger proportion of waste material (water, fly ash and slag) generated when burnt than for higher rank coals.

 

END USES: Steam generation in turbines for electrical generation. Feed for liquefaction or gasification.

 

IMPORTANCE: Approximately 8 to 10 Mt of sub-bituminous coal is required to generate 1 MW per year.

 

REFERENCES

 

Armstrong, W.M., Fyles, J.T., Guelke, C.B., Macgregor, E.R., Peel, A.L., Tompson, A.R. and Warren, I.H. (1976): Coal in British Columbia, A Technical Appraisal; B.C. Ministry of Energy, Mines and Petroleum Resources, Coal Task Force, 241 pages.
Cope, J.H.R., Duckworth, N.A., Duncan, S.V., Holtom, J.E.B., Leask, A.L., McDonald, K.A. and Woodman, S.P. (1983): Concise Guide to the World Coalfields; compiled by Data Bank Service, World Coal Resources and Reserves, IEA Coal Research.
Matheson, A. (1986): Coal in British Columbia; B.C. Ministry of Energy, Mines and Petroleum Resources, Paper 1986-3, 169 pages.
Smith, G.G. (1989): Coal Resources in Canada; Geological Survey of Canada, Paper 1989-4, 146 pages.

 

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BITUMINOUS COAL


A04

by Barry Ryan
British Columbia Geological Survey
 

Ryan, Barry (1995): Bituminous Coal, in Selected British Columbia Mineral Deposit Profiles, Volume 1 - Metallics and Coal, Lefebure, D.V. and Ray, G.E., Editors, British Columbia Ministry of Employment and Investment, Open File 1995-20, pages 13-15.

 

IDENTIFICATION

 

SYNONYMS: Metallurgical coal, coking coal, humic coal.

 

COMMODITIES (BYPRODUCTS): Coal, coke, (coal liquids, tar, gas).

 

EXAMPLES (British Columbia - Canada/International): Line Creek (082GNE020), Quintette
(093I 010, 011, 019, 020); Sydney coalfield (Nova Scotia, Canada), Sydney coalfield (Australia).

 

GEOLOGICAL CHARACTERISTICS

 

CAPSULE DESCRIPTION: Seams of black coal hosted by clastic sedimentary rocks. Coal is banded bright and dull. Generally hard with well developed cleats.

 

TECTONIC SETTINGS: Stable continental basins; shelves on the trailing edge of continents; foreland (molasse) basins; back-arc basins.

 

DEPOSITIONAL ENVIRONMENT / GEOLOGICAL SETTING: An area of slow sedimentation in fresh water with few or no marine incursions. Can be produced by fault blocks associated with strike-slip movement to limit sediment influx. Delta; shoreline swamp; raised swamp; lake; floating vegetation mats.

 

AGE OF MINERALIZATION: Generally older than Tertiary; major deposits are Cretaceous, Permian or Carboniferous in age.

 

ASSOCIATED ROCK TYPES: Sedimentary rocks exhibiting evidence of non-marine deposition; carbonaceous mudstones; siltstones and sandstones often with cross- stratification and other sedimentary structures of fluvial/alluvial or deltaic origin.

 

DEPOSIT FORM: Coal seams generally conform with regional bedding; sometimes seams are deposited in areas of local subsidence, such as fault-controlled blocks. Seams may be thickened/deformed by faulting, folding and shearing. Seams may pinch- out or split on a local or regional scale.

 

TEXTURE/STRUCTURE: Bituminous coal is usually composed mostly of clarain and vitrain. Footwall sediments are often penetrated by roots or weathered to clay (seatearth).

 

COAL SEAMS/ASSOCIATED MINERAL MATTER: Bituminous coal has Rmax values in the range of 0.5 to 2.0 %. In outcrop it can contain up to 15 % moisture. It usually contains a high percentage of the maceral vitrinite; at higher ranks liptinite is difficult to detect; the amount of fusinite is variable. Mineral matter is in the coal seams as rock bands, as finely intermixed material of authogenic or detrital origin (inherent mineral matter) and as secondary material deposited in fractures and open spaces. Inherent mineral matter includes pyrite, siderite and kaolinite. It may be dissimilar to that of the surrounding rocks.

 

WEATHERING: Weathering of the bituminous coal reduces the calorific value by oxidizing the carbon-hydrogen complexes. It also destroys the agglomerating (coke making) properties. Minerals such as pyrite oxidize to sulphates. Secondary carbonates are formed. These transformations may further damage the coking properties.

 

ORE CONTROLS: The geometry of the seam/seams is controlled by sedimentary features, such as extent of the delta, trend of the shoreline, and trend of sand-filled river channels. Deformation (faulting and folding) is also important.

 

ASSOCIATED DEPOSIT TYPES: Sub-bituminous coal (A03), anthracite (A05), shale-hosted Ni-Zn-Mo-PGE (E16), phosphate - upwelling type (F07).

 

COMMENTS: Bituminous coal is widely used for coke making by the steel industry because of its agglomerating properties.

 

EXPLORATION GUIDES

 

GEOCHEMICAL SIGNATURE: Geochemistry is generally not used as a prospecting tool for coal.

 

GEOPHYSICAL SIGNATURE: Bituminous coal has a low density. Resistivity is variable to high. Surface techniques include direct-current profiling, refraction and reflection seismic, and gravity. Subsurface or bore-hole techniques include gamma logs, neutron logs, gamma-gamma density logs, sonic logs, resistivity logs and caliper logs.

 

OTHER EXPLORATION GUIDES: Presence of: a down-slope coal bloom; nonmarine sediments; coal spar. Presence of methane escaping through the surrounding sediments.

 

ECONOMIC FACTORS

 

TYPICAL GRADE AND TONNAGE: Numerous tests quantify the coking ability of bituminous coal, they measure rheology, melting and petrographic properties of the coal as well as the chemistry of the ash. The gross heating value of bituminous coal is 27 to 33 MJ/kg on an ash-free moist basis. Net useable heat will be lower because of the presence of ash. Mine tonnages generally range from 10 to 1000 Mt.

 

ECONOMIC LIMITATIONS: Coal is a bulk commodity which is expensive to transport. Bituminous coal has a high market value because of its coking properties and high heating value. The ratio of tonnage to useable heat is good so that there is a lower proportion of waste material (such as water, fly ash and slag) generated than for other ranks of coals.

 

END USES: Coke; steam generation in turbines for electrical generation.

 

IMPORTANCE: Generally bituminous coal is used for coke making, weathered and non-agglomerating bituminous coal is utilized for power generation. Only source for coke used in the steel industry.

 

REFERENCES

Armstrong, W.M., Fyles, J.T., Guelke, C.B., Macgregor, E.R., Peel, A.L., Tompson, A.R. and Warren, I.H. (1976): Coal in British Columbia, A Technical Appraisal; B.C. Ministry of Energy, Mines and Petroleum Resources, Coal Task Force, 241 pages.
Cope, J.H.R., Duckworth, N.A., Duncan, S.V., Holtom, J.E.B., Leask, A.L., McDonald, K.A. and Woodman, S.P. (1983): Concise Guide to the World Coalfields; compiled by Data Bank Service, World Coal Resources and Reserves, IEA Coal Research.
Matheson, A. (1986): Coal in British Columbia; B.C. Ministry of Energy, Mines and Petroleum Resources, Paper 1986-3, 169 pages.
Smith, G.G. (1989): Coal Resources in Canada; Geological Survey of Canada, Paper 1989-4, 146 pages

 

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ANTHRACITE


A05

by Barry Ryan
British Columbia Geological Survey

 

Ryan, Barry (1995): Anthracite, in Selected British Columbia Mineral Deposit Profiles, Volume 1 - Metallics and Coal, Lefebure, D.V. and Ray, G.E., Editors, British Columbia Ministry of Employment and Investment, Open File 1995-20, pages 17-19.

 

IDENTIFICATION

 

SYNONYMS: Hard coal, stone coal, smokeless fuel.

 

COMMODITIES: Coal, carbon.

 

EXAMPLES (British Columbia - International/Canada): Klappan (104H 020,021,022), Panorama South (104A 082); Canmore (Alberta, Canada), Pennsylvania coalfields (USA).

 

GEOLOGICAL CHARACTERISTICS

 

CAPSULE DESCRIPTION: Seams of black coal hosted by clastic sedimentary rocks. Coal is well cleated with bright and dull bands. Anthracite often exhibits a high lustre and is not dusty.

 

TECTONIC SETTINGS: Stable continental basins; shelves on the trailing edge of continents; foreland (molasse) basins; back-arc basins.

 

DEPOSITIONAL ENVIRONMENT / GEOLOGICAL SETTING: An area of slow sedimentation in fresh water with few or no marine incursions. Can be produced by fault blocks associated with strike-slip movement to limit sediment influx. Delta; shoreline swamp; raised swamp; lake; floating vegetation mats.

 

AGE OF MINERALIZATION: Generally older than Tertiary; major deposits are Cretaceous, Permian or Carboniferous in age.

 

HOST/ASSOCIATED ROCK TYPES: Sedimentary rocks exhibiting evidence of non-marine deposition; carbonaceous mudstones; siltstones and sandstones often with cross- stratification and other sedimentary structures formed in fluvial/alluvial deltaic settings.

 

DEPOSIT FORM: Anthracite seams generally conform with regional bedding. Seams are often thickened/deformed by faulting, folding, shearing and thrusting. Seams may pinch-out or split on a local or regional scale.

 

TEXTURE/STRUCTURE: Anthracite is usually composed mostly of the lithotypes clarain and vitrain.

 

COAL SEAMS/ASSOCIATED MINERAL MATTER: Anthracite has Rmax values over 2.0 %. In outcrop anthracite can contain up to 5 % moisture. It usually contains a high percentage of the maceral vitrinite but because of the high rank the rheological and chemical differences between vitrinite and the inert macerals are small. Liptinite is difficult to identify at the anthracite rank. Mineral matter is in the coal seams as rock bands, as finely intermixed material of authogenic or detrital origin (inherent mineral matter) and as secondary material deposited in fractures and open spaces. Inherent mineral matter includes pyrite, siderite and kaolinite. It may be dissimilar to that of the surrounding rocks.

 

WEATHERING: Weathering of anthracite reduces the calorific value by oxidizing the carbon-hydrogen complexes. Minerals in the mineral matter will also oxidize. Pyrite oxidizes to sulphates. Secondary carbonates are formed.

 

ORE CONTROLS: Deformation (folding, faulting and thrusting) is very important. The regional geometry of the seam/seams may also be influenced by sedimentary features, such as extent of delta, trend of the shoreline, and trend of sand- filled river channels.

 

ASSOCIATED DEPOSIT TYPES: Bituminous coal (A04), shale-hosted Ni-Zn-Mo-PGE (E16), phosphate - upwelling type (F07).

 

COMMENTS: Anthracite is the highest rank coal. At this rank agglomerating properties have been destroyed and heating value decreased somewhat from the maximum obtained by low-volatile bituminous coal. Anthracite releases little smoke when burnt.

 

EXPLORATION GUIDES

 

GEOCHEMICAL SIGNATURE: Geochemistry is generally not used as a prospecting tool for anthracite.

 

GEOPHYSICAL SIGNATURE: Anthracite has a low density. Resistivity is variable to high. Surface techniques include direct-current profiling, refraction and reflection seismic, and gravity. Subsurface or bore-hole techniques include gamma logs, neutron adsorption logs, gamma-gamma density logs, sonic logs, resistivity logs and caliper logs.

 

OTHER EXPLORATION GUIDES: Presence of down-slope coal bloom; fresh water depositional structures; coal spar. Presence of anthracite seams can also be detected by escaping methane.

 

ECONOMIC FACTORS

 

TYPICAL GRADE AND TONNAGE: The heat value of anthracite is good and similar to that of medium-volatile bituminous coal. Gross heating values are 30 to 33 Mj/Kg on an ash-free moist basis. Net useable heat will be lower because of the presence of ash. The mine reserves of anthracite generally range from 10 to 100 million tonnes. They are generally smaller than the strip or open pit thermal or metallurgical coal mines.

 

ECONOMIC LIMITATIONS: Anthracite is a bulk commodity which is expensive to transport. Anthracite as low-ash lumps can be more than twice as valuable as bituminous coal, in which case it is shipped widely. Sold as fine anthracite briquettes with a moderate ash content, it has about the same dollar value as bituminous thermal coal.

 

END USES: Source for carbon. Specialized smelting applications, smokeless fuel for heating.

 

IMPORTANCE: As low-ash large lumps it is an important source of carbon in the chemical industry.

 

REFERENCES

Armstrong, W.M., Fyles, J.T., Guelke, C.B., Macgregor, E.R., Peel, A.L., Tompson, A.R. and Warren, I.H. (1976): Coal in British Columbia, A Technical Appraisal; B.C. Ministry of Energy, Mines and Petroleum Resources, Coal Task Force, 241 pages.
Cope, J.H.R., Duckworth, N.A., Duncan, S.V., Holtom, J.E.B., Leask, A.L., McDonald, K.A. and Woodman, S.P. (1983): Concise Guide to the World Coalfields; compiled by Data Bank Service, World Coal Resources and Reserves, IEA Coal Research.
Matheson, A. (1986): Coal in British Columbia; B.C. Ministry of Energy, Mines and Petroleum Resources, Paper 1986-3, 169 pages.
Smith, G.G. (1989): Coal Resources in Canada; Geological Survey of Canada, Paper 1989-4, 146 pages.

 

 

BC Profile # Global Examples B.C. Examples
A01 Ireland, Ontario, New Brunswick Fraser Delta, North Coast
 A02 Estevan (Saskatchewan) Skonun Point (Graham Island)
 A03 Highvale (Alberta), Powder River Basin (Wyoming) Hat Creek, Princeton
 A04

Gregg River (Alberta), Sydney Coalfield (Nova Scotia) 

Quintette, Bullmoose, Greenhills, Fording
 A05 Pennsylvannia Coalfields, Canmore (Alberta) Mt Klappan