4.2.1 Comments - Mineralogy
4.3 Alteration Type
4.4 Deposit Character
4.5 Deposit Classification
4.6 Deposit Type
4.7 Age of Mineralization
4.8 Isotopic Age
4.9 Material Dated
4.10 Dating Method
4.11 Deposit Configuration
4.11.2 Shape Modifier
4.11.3 Deposit Dimension
4.13 Comments - Structural and Age
When coding online select the options from the corresponding list boxes.
Online help is also available from the MINFILE/www online coding card.
4.1 COMMODITIES(*)(R19) (E19)
The commodity fields are used to identify the presence of an element or substance of economic potential or interest. The commodities present in the mineral occurrence are to be listed, in decreasing order of importance, based on economic significance. The commodity may be present in any amount and it is not the prerogative of the individual coder to identify commodities based on economic or quantitative criteria. Commodities produced as an economic product from mining activities are identified in the Production and Inventory portion of the database. The commodities identified in the Inventory/Production portions MUST be included in the commodities list for the occurrence. The database will accept up to 15 different commodities per occurrence. Listed commodities should normally have a corresponding mineral in the significant mineral category.
The search codes for commodities consist of two-character standard elemental chemical symbols or two-character codes made up for industrial minerals and other commodities. Appendix II contains a complete listing of the current commodity search codes. New codes may be added to the master table if required.
Examples: AU=gold, PT=platinum, LS=limestone, JD=jade
Appendix VIII is a glossary of historic and equivalent mineral names and should be used to identify equivalent names or synonyms for the commodities.
4.2 MINERALOGY(*)(R20) (E20a,b)
The mineralogy is described by SIGNIFICANT, ASSOCIATED and ALTERATION minerals. Minerals for each category are entered in decreasing order of significance.
Minerals included in the SIGNIFICANT (economic) category need not be present in economic concentrations but should contain some element of economic interest. ASSOCIATED (gangue) minerals are those present which either form a host matrix to rocks of economic interest or are those related to the occurrence of SIGNIFICANT minerals. ALTERATION minerals are those associated with the alteration process.
The database will accept up to sixteen minerals in the SIGNIFICANT category, and eight minerals each in the ASSOCIATED and ALTERATION categories. All minerals and their context should be identified in the Capsule Geology. Care should be taken not to duplicate minerals by using synonyms (e.g., FLUORSPAR and FLUORITE). See Appendix VIII for a short list of historic and equivalent mineral names and their current aliases; this will be of assistance where older references are consulted. Minerals may occur in more than one category (e.g., pyrite may be included as a Significant and an Alteration mineral if appropriate).
Appendix III is the complete list of mineral search codes which may be used in any of the three categories, SIGNIFICANT (economic), ASSOCIATED (gangue) or ALTERATION minerals. Appendix I contains the recommended derivation technique used to define codes for minerals not already included in the master table. The resulting code must be unique for each mineral. Recommended new codes for minerals are approved and added to the code tables by the database administrator.
4.2.1 COMMENTS - MINERALOGY (C02,C03,C04): Each of the SIGNIFICANT, ASSOCIATED and ALTERATION mineral categories has an area available for text comments pertinent to understanding the mineralogy. Unlimited 70-character lines are provided for Significant, Associated, and Alteration comments.
4.3 ALTERATION TYPE(R21) (E21)
This field indicates the presence of various alteration types based on the alteration and gangue mineralogy identified. A maximum of five alteration types may be input per occurrence from the following table:
|The indicated mineralogy is intended as a general guide, not as a geologically comprehensive definition. Alteration types may be gradational from one to another.|
|ALBITIC (SODIUM SILICATE)
Introduction of, or replacement by, ALBITE, usually replacing a more calcic plagioclase. It may result from strong sodium metasomatism and addition of sodium to the original rock or it may result by leaching of other cations in the rock and apparent enrichment of sodium. Typical mineral assemblages are ALBITE, PARAGONITE (sodium-rich sericite), CHLORITE, and QUARTZ; generally accompanied by ORTHOCLASE, ANKERITE, or other carbonate minerals.
Introduction of, or replacement by, ALUNITE. This alteration is caused by extreme hydrolytic leaching of wallrocks in the presence of sulphate. The conditions are oxidizing with an abundance of sulphate ions. The most common mineral assemblage is ALUNITE with some form of silica: QUARTZ, CHALCEDONY, CRISTOBALITE, TRIDYMITE, or OPAL. Other minerals present commonly include KAOLINITE, SERICITE, DIASPORE, BARITE, JAROSITE, RUTILE, ZUNYITE, PYRITE, and HEMATITE.
Intermediate argillic alteration is the replacement or alteration of feldspars to form predominantly clay minerals. These include the KAOLINITE group: DICKITE, KAOLINITE, HALLOYSITE, and METAHALLOYSITE; the SMECTITE (MONTMORILLONITE) group; the ILLITE group; and the amorphous clays (ALLOPHANE). Mineral assemblages characteristic of advanced argillic alteration caused by hydrothermal solutions at low and moderate temperatures are dominated by KAOLINITE group clay minerals. DICKITE, KAOLINITE, DIASPORE, and PYROPHYLLITE may occur with SERICITE, QUARTZ, ALUNITE, PYRITE, TOURMALINE, TOPAZ, ZUNYITE, and AMORPHOUS CLAYS (ALLOPHANE).
Introduction of, or replacement by, BIOTITE.
Introduction of, or replacement by, CARBONATES. Magnesium, iron, calcium, and manganese carbonates are common. These are CALCITE, DOLOMITE, ANKERITE, and SIDERITE.
The replacement by, conversion into, or introduction of CHLORITE. This alteration may result from a number of disparate metasomatic processes. Mineral assemblages comprise CHLORITE, with subordinate SERICITE, QUARTZ, and PYRITE.
A process involving reactions between primary magmatic minerals and the water-rich solutions that separate from the same body of magma at a late stage in its cooling history. These processes may result in SILICIFICATION, SODIUM SILICATE (ALBITIZATION), POTASSIUM SILICATE, TOURMALINIZATION and GREISENIZATION as pervasive, selectively pervasive, cavity filling and/or vein-controlled modes of alteration.
The hydrothermal introduction of EPIDOTE into rocks or the alteration of rocks in which plagioclase feldspar is albitized, freeing the anorthite molecule for the formation of EPIDOTE and ZOISITE, often accompanied by chloritization. These processes are characteristically associated with metamorphism.
Widespread alkali metasomatism of quartzofeldspathic country rocks in the environs of carbonatite complexes and/or alkalic igneous rocks. FENITES are characterized by FELDSPATHOIDS, and ALKALI FELDSPARS (POTASH FELDSPAR, ALBITE), PYROXENES (AEGERINE, AEGERINE-AUGITE), and AMPHIBOLES (RIEBECKITE-ARFVEDSONITE series).
A type of alteration whose minerals are enriched in fluorine, boron, and the alkali metals (Na, K, and Li). The characteristic minerals include TOURMALINE, TOPAZ, MUSCOVITE, ZINNWALDITE, FLUORITE, ALKALI FELDSPARS, and/or KAOLINITE.
HEMATITE is the principal mineral product and varieties may be granular, specular, or more rarely, earthy. The latter is generally of supergene origin and is associated with clay minerals. The style of hematite alteration is pervasive, selectively pervasive, and vein-controlled.
The separation, selective removal, or dissolving-out of soluble constituents from a rock, soil, or orebody by the natural action of percolating water.
A process whereby an area is modified by surface waters, and/or reaction with oxygen (e.g., sulphides altered to oxides and carbonates). A GOSSAN represents an oxidized zone formed by the oxidation of sulphides and the leaching-out of the sulphur and most metals, leaving hydrated iron oxides and rarely sulphates. Minerals include LIMONITE, HEMATITE, and others.
|POTASSIUM SILICATE (POTASSIC)
Hydrothermal alteration resulting from potassium metasomatism, commonly accompanied in calcalkaline rocks by removal of calcium and sodium. Characteristic major minerals are POTASSIUM FELDSPARS (ADULARIA, ORTHOCLASE, MICROCLINE), BIOTITE or CHLORITE, SERICITE, and QUARTZ, with common ALBITE, ANHYDRITE, FE-MG CARBONATE, and APATITE.
The result of low pressure-temperature alteration. The propylitic assemblage consists of EPIDOTE, CHLORITE, ZOISITE, CLINOZOISITE, SERICITE, MG-FE-CA CARBONATES, PYRITE, and sometimes ALBITE-ORTHOCLASE, all involved in partial replacement of wallrock minerals. HEMATITE, JAROSITE, and GOETHITE are also common.
Introduction of, or replacement by, PYRITE. A common process of hydrothermal alteration.
LISTWANITE. A mineralogic assemblage that results from the carbonatization of serpentinized ultramafic rocks. A distinctive alteration suite consisting of green chromium-bearing mica (MARIPOSITE, FUCHSITE) with QUARTZ, CARBONATE, LIMONITE and MAGNESITE.
A metasomatic alteration of a protolith during serpentinization. RODINGITE is a product of this process and is a massive dense calcsilicate rock typically rich in GROSSULAR GARNET and DIOPSIDE. Accessory minerals include combinations of IDOCRASE, CLINOZOISITE, ZOISITE, VESUVIANITE, CHLORITE, PREHNITE, and SERPENTINE.
A very abundant and widespread alteration with a characteristic mineral assemblage of SERICITE, QUARTZ, and PYRITE. Sericitization is often the alteration type most closely associated, spatially, with sulphide ore and is a hydrothermal, deuteric, or metamorphic process involving the introduction of, alteration to, or replacement by SERICITIC MUSCOVITE.
The process of hydrothermal alteration by which magnesium-rich silicate minerals (e.g., olivine, pyroxenes, and/or amphiboles in dunites, peridotites, and/or other ultramafic rocks) are converted into or replaced by serpentine minerals. Minerals include SERPENTINE, CHRYSOTILE, BRUCITE, TALC, MAGNETITE, and MAGNESITE (CARBONATES).
The introduction of, or replacement by, SILICA, generally resulting in the formation of fine-grained QUARTZ, CHALCEDONY, or OPALINE SILICA (OPAL), which may fill pores and replace existing minerals.
Silication (silicate alteration) is also known as pyrometasomatic, contact metasomatic, and igneous metamorphic mineralization. The process is one of hydrothermal alteration of carbonate rocks. The altered rocks resulting from the process are called SKARNS or TACTITES. Not all skarn protoliths are carbonate rocks; volcanic and plutonic igneous rocks and aluminosilicate sedimentary rocks may be silicated if their Ca, Mg, and/or CO2 contents are sufficiently high. A wide variety of silicate minerals occur with iron oxides and/or sulphides and with a variety of other minerals of economic interest. Common minerals in the silicated rocks include: GARNETS: ANDRADITE and GROSSULARITE (ALMANDINE is more rare); EPIDOTE and CLINOZOISITE; DIOPSIDE-HEDENBERGITES; IDOCRASE (VESUVIANITE); WOLLASTONITE; TREMOLITE-ACTINOLITE; BIOTITE-PHLOGOPITE; CHLORITES; POTASSIUM and PLAGIOCLASE FELDSPARS.
TALC forms as an alteration product of magnesium silicates such as olivine, pyroxenes and amphiboles, or by the reaction between magnesium and silica. Minerals commonly associated with TALC are CHLORITE, DOLOMITE (CARBONATE), TREMOLITE, ANTHOPHYLLITE, ANTIGORITE, SERPENTINE, MAGNESITE, MAGNETITE, and CHROMITE. Common geologic settings for TALC formation are 1) within regionally metamorphosed and/or hydrothermally altered ultramafic rocks, 2) in association with schists, generally chloritic, 3) with dolomite and magnesite, or 4) with mafic volcanics.
Introduction of, or replacement by, TOURMALINE as pervasive, selectively pervasive, and vein-controlled alteration.
Introduction of, alteration to, or replacement by, a mineral or minerals which have ZEOLITES as distinctive, though not necessarily abundant, gangue minerals. Zeolitization results from the passage of relatively low-temperature, near-neutral, hydrothermal solutions that cause recombination of sodium, calcium, and/or potassium in the wallrocks. ZEOLITES most commonly occur as alteration products of volcanic glass and calcium-rich plagioclase feldspar and are associated with alteration minerals which include ADULARIA, PREHNITE, PUMPELLYITE, and minerals of the propylitic facies, particularly EPIDOTE, ALBITE, and CARBONATES. The most common ZEOLITES include CLINOPTILOLITE, MORDENITE, ANALCIME, HEULANDITE, LAUMONTITE, and WAIRAKITE.
||Insufficient information to allow alteration type.|
4.4 DEPOSIT CHARACTER
The deposit character describes the style of the mineralization or the significant geological feature(s) associated with the mineralized hostrocks. The database will accept up to four Deposit Characters for each occurrence and these are ranked in order of importance. This field is mandatory and at least one characteristic must be identified.
A complete description of the characteristics of an occurrence should be incorporated in the Capsule Geology.
Occurrences in which mineralization occurs within one or more simple or complex veins, or vein sets which may be associated with fault or shear zones.
Occurrences in which mineralization occurs within a network of veinlets in the country rock.
Mineral occurrences hosted and/or controlled by the angular, broken rock fragments held together by a mineral cement or in a fine-grained matrix. The breccia may be sedimentary, igneous or tectonic in origin.
Mineralization in pipes which are generally funnel shaped or cylindrical,, particularly mineralized breccia pipes, diatremes, etc.
Occurrences within material whose particles are not cemented together. May occur at surface or at depth but is usually assumed to be surficial material.
Mineralization in a lenticular or rodlike shape with either diffuse or sharp boundaries. May vary from a few centimetres to tens of metres in size.
Mineralization within a tabular succession with different components of igneous, sedimentary or metamorphic rocks which can be identified by mineralogical, textural or structural criteria.
General term for mineralization confined by physical or chemical controls to specific stratigraphic units. Such deposits can include veins, lenses, layers, etc. which may or may not be transgressive relative to the enclosing stratigraphy.
Specific term used for mineralization which is generally sheet-like in form and concordant to layering in enclosing rocks. Generally applied to deposits such as sedimentary exhalative (SEDEX) and volcanogenic massive sulphide (VMS) deposits.
Mineralization which is structurally conformable with the major mineralogical textural or structural fabric of the hostrock.
Mineral occurrences which are not parallel to the major mineralogical, textural or structural fabric of the hostrock.
Mineralization which constitutes a larger percentage of the rock volume than the matrix or gangue minerals.
Mineralization which occurs as scattered grains in the hostrock. There is no genetic connotation.
A tabular zone of rock that has been crushed and brecciated by many parallel fractures due to shear strain. Such an area is often mineralized by ore-forming solutions.
Insufficient information to allow classification.
4.5 DEPOSIT CLASSIFICATION
Deposit classification is a general interpretation of the origin of an occurrence based on the best available geological data. The database will accept up to four classifications for any given occurrence.
This field is mandatory and at least one classification must be assigned. The coding of deposit classification should be ranked, that is, provide the order in which the classifications are to be entered. The ranked order will be reflected in the printout.
A genetic description should be incorporated in the Capsule Geology and should indicate the geological evidence for the interpretations.
Deposits form by a solution and deposition mechanism by which new (ore) minerals grow and replace existing minerals. Usually used in the context of ore minerals replacing carbonate minerals or other soluble rock.
Mineralization is directly related to a crystallization process in magma, exclusive of pegmatites. The deposits may constitute the entire rock mass, form a compositional layer, or occur as disseminated minerals in an igneous rock.
Deposits form by processes directly related with volcanism. They are considered to have been produced through volcanic agencies and are demonstrably associated with volcanic phenomena.
Stratiform and/or stratabound deposits form in clastic and carbonate sequences with no strong volcanic association.
Deposits form contemporaneously with, and by essentially the same processes as, the enclosing rock.
Deposits form later than the enclosing rock.
Deposits form by precipitation of ore and gangue minerals from heated metalliferous, hydrous fluids in fractures, faults, breccia openings or other spaces, by replacement or open-space filling. Fluid temperatures may range from 50 to 700 degrees Celsius, but are generally below 400 degrees Celsius.
Deposits form by mechanical concentration or chemical alteration in a zone of weathering (e.g., laterite, limonite, clay, etc.)
Mineralization is spatially and genetically related to igneous intrusions which are generally felsic but range widely in composition. The intrusions are epizonal and invariably porphyritic. Multiple intrusive events, dike swarms, and intrusive breccias are characteristic. Hosts for the intrusions can be any rock type, and range from unrelated country rocks to comagmatic extrusive equivalents. Mineralization and alteration form large zones that exhibit lateral and vertical zoning. Economic minerals occur throughout a large volume of rock as disseminated grains, in stockworks, and veins.
Mineralization is directly related to contact metamorphic or metasomatic alteration caused by the intrusion of igneous rock. Skarn may be considered a more specific division of this category.
Deposits are related to pyrometasomatic, contact metasomatic, and igneous metamorphic processes. Skarn protoliths are generally carbonate rocks but volcanic, igneous and aluminosilicate sedimentary rocks can also be hosts. A wide variety of silicate minerals occur with iron oxides and/or sulphides and with a variety of other minerals of economic interest.
Mineralization is directly associated with the formation of pegmatites. Pegmatites represent the last and most hydrous portion of a magma to crystallize and are found as irregular dikes, lenses, or veins, especially at the margins of batholiths. Their composition may be simple or complex and may include rare minerals rich in such elements as lithium, boron, fluorine, niobium, tantalum, uranium, and rare earths.
Deposits form in unconsolidated surficial material as a result of mechanical, chemical, or residual weathering processes.
Deposits form by the deposition of soluble components caused generally by evaporation in salinas (salt lakes) and sabkhas (low-lying salt flats) and by precipitation from subsurface brines in both marginal marine and inland desert basins. Principal ore minerals include anhydrite, halite, gypsum, sodium sulphate, potash, and others.
Deposits form from the issuance of volcanic, sedimentary or igneous derived fluids onto or very close to the sea floor.
Mineralization occurs within, or controlled by, a breccia-filled volcanic pipe formed by gaseous explosion (e.g., kimberlite).
Deposits form at high structural levels, at some distance from intrusions commonly in volcanic terranes. Mineralization occurs at surface to a maximum depth of approximately 1000 metres at temperatures generally less than 285 degrees Celsius. Veins are the most common ore host but breccia zones, stockworks, and fine grained bedding replacement zones also occur. Ore and associated minerals are deposited dominantly as open-space filling with banded, crustiform, vuggy, drusy, colloform, and cockscomb textures. Repeated cycles of mineral deposition are evident.
Deposits form at considerable depth (1 to 5 kilometres) from tectonically driven, large scale, deeply circulating fluid systems in the temperature range of 200 to 300 degrees Celsius. They are structurally controlled, multiple, massive to ribboned vein systems with considerable lateral and vertical extent, predominantly in island arc and sedimentary rocks, and remnant slices of oceanic material.
This term identifies any hydrocarbon that may be used for fuel. Includes, but is not limited to, petroleum, natural gas, coal, peat, and oil shale.
Minerals develop by an isochemical process when no introduction of material from an external source takes place (e.g., kyanite, garnet, etc.).
Industrial minerals, including stone and rocks, may be defined as those naturally occurring materials used to build structures or supply products that are useful to an industrialized society. Since industrial minerals exclude the ores of metals, they have been called the "nonmetallics". Gems and art objects are valuable for their intrinsic properties, but because they are not used in the sense of structures or products, they are not included. Industrial-grade diamonds and semiprecious minerals, however, are useful to industry because of their hardness and are included under abrasives. Listed below are commodities which are considered by MINFILE to be Industrial Minerals.
||There is insufficient information to define a deposit classification.|
4.6 DEPOSIT TYPE(R30) (E30)
Deposit types are based on the British Columbia Mineral Deposit Profiles of the BC Geological Survey. Please refer to this link for a listing of all deposit types.
The Deposit type is an attempt to define a deposit based on its characteristics and includes/implies an explanation of these characteristics in terms of geological processes. The database will accept up to four Deposit types for any given occurrence.
This field is optional since there is often not enough information to define many occurrences as a specific deposit type. The coding of deposit type is ranked, using the most important type as the first ranked. The ranked order will be reflected in the printout.
A thorough deposit description should be incorporated in the Capsule Geology and should indicate the geological evidence for any and all interpretations.
4.7 AGE OF MINERALIZATION(R24) (E24)
The geologic age of the mineralization is indicated with an appropriate era, period or epoch. A complete listing of acceptable codes is provided in Appendix V Stratigraphic Age Codes and is available for online coding with the list box. This is an optional field and should be used only if substantial evidence supports the data. This evidence must be stated and referenced in the Structural and Age Comment field and in the Capsule Geology. If the age of mineralization is known then the Isotopic age and Material Dated fields should also be filled in. When coding via the MINFILE/www online coding card select the age of mineralization from the list box.
4.8 ISOTOPIC AGE(of mineralization) (R22)
|This is a twenty-character, free-format field for the age of mineralization in millions (Ma) or billions (Ga) of years. Associated age dating errors should be included (e.g., 48.7 +/- 1.2 Ma). The Structural and Age Comment field must identify the reference used.
Okulitch, A.V. (1999): Geological Time Chart 1999, Geological Survey of Canada, Open File 3040
Grant, Brian (2003): Geoscience Reporting Guidelines
PDF version or JPG
4.9 MATERIAL DATED(R22)
This is a thirty-character, free-format field to identify the actual material(s) used in the dating procedure (e.g., biotite, hornblende, fossil, etc.). The information is used to support the Isotopic Age field.
4.10 DATING METHOD(R22) (E22)
The dating method used must be identified for information entered in the Isotopic Age field.
Valid dating methods are listed in the adjacent table:
4.11 DEPOSIT CONFIGURATION(E01)
Three optional fields are available to identify the shape, structural character and size of a mineral occurrence. These fields are usually reserved for those occurrences which have received sufficient exploration and development to have outlined a deposit.
4.11.1 SHAPE OF DEPOSIT (R06) (E06): An appropriate description of the shape of the deposit is selected from the list below. The field is used only if sufficient information is available to identify the shape. The shape should reflect gross dimensions and discount minor irregularities. The coding geologist should identify the shape of the mass of the ore minerals present and not just the host setting. For example, mineralization within a vein or fault may be cylindrical or bladed and not necessarily tabular.
Descriptions of the shape of a deposit are defined as follows:
Regular - The deposit is regular in shape and is approximately the same dimension in all directions. Shapes range from spheroidal to tetrahedral;
Tabular - The deposit has two long dimensions and one short dimension. This would include veins, sills and dikes, etc.;
Cylindrical - The deposit has one long and two short dimensions which are approximately equal. This would include pipes, ore shoots, etc.;
Bladed - The deposit has one long, one medium and one short dimension. Many deposits hosted by shear/fault zones or dikes will belong to this category;
Irregular - The deposit has no discernible regularity of form.
|4.11.2 SHAPE MODIFIER (R04) (E04): A structural modifier is used to support the data in the deposit shape field. This field cannot be used unless deposit shape is identified. The database will accept up to two modifiers.
|Other (specify in comment field)
4.11.3 DEPOSIT DIMENSION (E01): The deposit dimensions are defined in metres, in a sequence of maximum to minimum dimensions (Example: 376 x 230 x 4). Each of the three dimension fields will accept up to four digits.
Specific directional measurements may be entered which are pertinent to understanding the orientation and/or setting of a mineral occurrence. One measurement for each of strike/dip and trend/plunge may be entered per occurrence.
Strike - The strike direction, as measured in the field, may be entered as a three-digit number from 001 to 360 degrees. Magnetic bearings should be converted to azimuth. Leading zeros should be included in the coding.
Dip - The dip, from horizontal to vertical, may be entered as two digits from 01 to 90 degrees. Dip should be further defined using a directional indicator of N, S, E or W for the four major compass directions. (Dip is perpendicular to strike.)
Trend - The azimuth of the trend, as measured in the field, may be entered as a three-digit number from 001 to 360 degrees. Leading zeros should be included.
Plunge - Plunge, from horizontal to vertical, may be entered as two digits from 01 to 90 degrees. (Plunge is in the direction of structural trend.)
An unlimited number of 70-character lines of text may be added in the structural comment field to clarify structural or age dating information. If age dating information is included then the reference should be stated here. Also, when dimensions and attitude are given, the specific ore body that these refer to should be identified. Optional text comments pertinent to understanding the mineralogy can be added to the significant, associated and alteration comment fields.