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Ministry of Energy, Mines and Petroleum Resources
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Mineral Exploration and Mining
Mineral Exp ...
a layer of rock, usually
a term used to describe the solid rock that underlies soil or other unconsolidated material.
mineral matter deposited between rock-particles so that they stick together as a solid mass. The commonest cements in sedimentary rocks are silica (quartz) and calcite.
a homogeneous solid with a definite chemical composition and ordered atomic structure, bounded by naturally-formed plane faces. One of several
a mineral can take.
Dyke (or dike)
a sheet-like igneous intrusion normally intruded in a more or less vertical position and so crosscutting layering in host rocks. Similar intrusions that parallel layering are called
. Rocks forming dykes are usually fine to medium-grained or porphyritic.
a naturally occurring shaking motion of the Earth's surface.
are caused when stress, building up within rocks of the Earth's crust, is released in a sudden jolt.
the general term for the wearing away of rocks including loosening, breaking up, physical and chemical disintegration, and solution of the rock. Also includes the transport of the fragments.
the products of igneous activity at the Earth's surface. Includes both
which are outpourings of molten rock on the surface, and
(pyroclastics) made up of solid, broken fragments ejected from the volcano.
a layered arrangement of minerals in a rock, usually
the remains, impression or trace of parts of an animal or plant in a rock.
the science of the Earth, its composition, structure, processes and history.
sediments which form as a result of the actions of ice or glaciers.
igneous rocks formed at shallow depths within the crust. They are usually fine to medium-grained or
rocks formed by the crystallization of minerals from molten material or magma as it cools
an igneous rock formed by the forceful movement and cooling of magma into a body of rock below the Earth's surface. Includes both
rocks which have formed from pre-existing rocks due to changes in temperature, pressure, stress or chemistry.
minerals are naturally occuring inorganic substances with a definite and predictable chemical composition and
. More than two thousand three hundred different types of minerals have been identified. Luckily many are rare and the common rocks are made up of a relatively
the study of rocks, their properties and origins.
Physical Properties of minerals
the physical properties of a mineral reflect in a close way the crystal structure and chemical compositon of the mineral. However, they are often easier to determine. They are of great practical significance not only to aid in the identification of the mineral, but also in determing the possible industrial uses of the mineral. The commonest physical properties include:
- the external appearance of a mineral or aggregates of the mineral, e.g., crystalline, fibrous, stalactitic, dendritic (plant-like), etc.
- colour observed in a mineral sample in white light. With experience, colour can be one of the most valuable of diagnostic properties.
- the colour of the powdered mineral, which may differ from the body colour of the unpowdered mineral. Usually determined by drawing the mineral across a piece of unglazed, white porcelain known as a
- whether the mineral allows light to pass through it. Minerals can be transparent, translucent or opaque.
- the ability of a mineral to resist abrasion or scratching. Measured on a relative scale from 1 - 10 known as
in which minerals of higher number scratch those of lower numbers. For simple field determinations, a fingernail has an hardness of about 2.5 and the blade of a penknife about 5 - 5.5.
- The characteristic appearance of a mineral in reflected light, e.g., metallic, pearly, earthy, greasy, etc.
- the way that the mineral breaks; if it breaks along planar surfaces related to the crystal structure it is said to show
, but if it breaks irregularly is said to show
- the measure of the mass per unit volume of a mineral. In simplest terms, some minerals will be heavier than others for similar sized samples, e.g. gold is denser than quartz.
intrusive igneous rocks that form at some depth. They are usually medium to coarse-grained and include rocks such as
an igneous rock in which comparatively large crystals,
, occur within a distinctly finer-grained ground mass.
a consolidated collection or aggregate of mineral material .
an amateur rock and mineral collector.
rocks formed by the accumulation of fragments, or the precipitation of dissolved material, that result from the weathering of pre-existing rocks.
loose sediment that has not been cemented or otherwise converted to solid rock.
a crack or fissure in a rock that is infilled with mineral matter. Veins can vary in thickness from less than a millimetre to several tens of metres. Similarly, thay can vary in length up to several hundreds of metres.
decribes a volcanic rock that has holes,
, that were once gas bubbles in the molten lava. The holes are often later infilled with minerals, such as calcite or quartz, and are then referred to as
rocks which result from volcanic action at, or near, the surface of the Earth such as lava flows or ash deposits.
a hill resulting from
igneous activity. Volcanoes are described as
(presently or recently in action),
(inactive for some time, but liable to erupt again) or
(no longer active and unlikely to erupt again).
the disintegration of rocks on the Earth's surface by the action of rain, frost, heat, wind, etc.