Glossary of geoscience terms

Glossary of Geoscience terms

Banded ore

an ore consisting of alternating layers of ore minerals and gangue material and/or host rock.

Conchoidal fracture

a break in a solid that results in a smoothly curved surface.

Conjoin

two or more artefacts that have been fitted together by an archaeologist.

Crust

the thin, outer rocky shell of Earth.

Cubic cleavage

a cubic surface resulting from breaks along three, intersecting 90° planes.

Density

the ratio of an object's mass to its volume. (measured as grams per centimetre cubed: g cm3)

Disseminated ore

an ore consisting of fine ore mineral particles that are dispersed throughout the host rock.

Element

a pure substance made of only one type of atom.

Enrichment

the processes by which the relative amount of one constituent mineral or element contained within a rock is increased.

Epithermal

a term applied to relatively low-T (e.g. 100° C - 200° C) hydrothermal processes.

Fool's Gold

usually applied to fine-grained iron pyrite and chalcopyrite.

Fossil

evidence of past life preserved in rock.

Gangue

part of a mineral deposit from which a metal or metals are not extracted. It is important to note that gangue minerals in one mineral deposit may be ore minerals in another (e.g. pyrite, baryte, fluorite). The most common gangue minerals are quartz, calcite, fluorite, siderite and calcite

Gossan

the leached and oxidised near-surface part of an ore deposit, usually composed of iron oxide/hydroxide and quartz.

Grade

the metal content of an ore.

Hafting

the fitting of a handle to an artefact such as a shaped stone or piece of bone.

Host rock

the body of rock surrounding an ore body.

Hypothermal

a term applied to relatively high temperature (e.g. 300° C - 500° C) hydrothermal processes.

Igneous Rock

a rock formed through the cooling and solidification of magma (instrusive) or lava (extrusive).

Inner Core

the primarily solid centre of Earth that is mainly composed of iron-nickel alloy.

Knapping

the process by which a rock is shaped by striking it with a harder object, such as a hammer stone.

Limonite

a common term used for a mixture of amorphous iron oxides and hydroxides.

Lithification

the process whereby sediment is converted into rock by the action of compression and cementation.

Lode

an old term for an ore deposit consisting of the ore itself along with the host rock.

Mafic

a silicate mineral or igneous rock that is rich in magnesium and iron.

Mantle

the layer between the crust and the outer core of Earth.

Mass

a measure of a body's resistance to a change in velocity. (measured in kilograms (kg)).

Massive ore

an ore consisting of mostly ore minerals with very little gangue and/or host rock.

Matter

is anything that takes up space and has a measurable mass.

Mesothermal

a term applied to intermediate temperature (e.g. 200° C - 300° C) hydrothermal processes.

Metallogenic Provinces

are regions in which a series of mineral deposits possess common characteristics.

Metamorphic Rock

a pre-existing rock whose mineralogy and/or texture has been changed by processes within the Earth.

Meteorite

Extraterrestrial debris that lands on Earth’s surface.

Mineral

a naturally occurring, inorganic solid with a definite chemical composition and a regular atomic structure. From this basis comes all of a mineral's physical properties.

Mineral Deposit

any naturally occurring body of minerals which is wholly or partly of economic value. The value lies in the ore minerals and not the body of minerals as a whole.

Mineralisation

an anomalous concentration of an element of economic importance within a rock body. Mineralisation may be visible to the naked eye (as is normally the case with base metals such as copper, lead and zinc) or invisible (as is normally the case with gold). The term mineralisation is a geological one and has no economic implications.

Mispickel

an old name for the mineral arsenopyrite.

Ore body

the parts of a mineral deposit where the ore minerals are concentrated into an economically extractable mass.

Ore mineral

a mineral from which a useful metal (or non-metal such as fluorite) may be extracted profitably.

Outer core

the fluid layer of mostly iron and nickel that lies between the mantle and inner core.

Peacock Ore

a popular term for the copper iron sulfide mineral, bornite.

Pitchblende

the most common ore of uranium, which is dominantly composed of the mineral uraninite.

Primary ore

ore minerals formed from either hot magmas or fluids.

Reef

a gold-bearing quartz vein.

Rock

a naturally occurring aggregate of minerals.

Sedimentary Rock

rocks formed by the breakdown, deposition and lithification of pre-existing rocks.

Specific gravity

the density of a substance to that of water (weight divided by loss of weight in water).

Tinstone

a popular name for cassiterite, the main ore of tin.

Vein

a tabular or sheet-like body of minerals that has intruded into joints or fissures in the rock.

Wad

a common term used for fine-grained mixtures of manganese oxide minerals.

Wallrock

the country rock (surrounding rock) of a vein or ore body.

Weight

the force with which an object of certain mass is attracted by gravity to the Earth or another body. (measured in Newtons : N)