Glossary Rocks Flashcards
Minerals
A natural substance that makes up rocks.
Magma
A very hot mixture of molten rock and gases, just below the Earth’s surface, that has come from the mantle.
Sediments
Matter that settles to the bottom of a liquid.
Lithosphere
The outer layer of the Earth, consisting of the upper mantle and crust.
Native Elements
Elements found uncombined in the Earth’s crust.
Crystal
Highly transparent glass with a high refractive index.
Lustre
Appearance of a mineral caused by the way it reflects light. Minerals such as glassy, waxy, metallic and silky.
Streak
colour of a mineral as a fine powder, found by rubbing it onto an unglazed white ceramic tile.
Hardness
A measure of how difficult it is to scratch the surface of a solid material.
Igneous Rock
Rocks that form from the cooling of lava or magma as it is thrown through the air from a volcanic eruption.
Extrusive Rock
igneous rock that forms when lava cools above the Earth’s surface
Pumice
A pale rock that forms when frothy lava cools in the air. Pumice often floats on water as it is very light and full of holes that once contained gas.
Scoria
A dark, igneous rock formed from gassy lava that cools quickly
Abrasive
A property of a material or substance that easily scratches another
Basalt
A dark, igneous rock with small crystals formed by fast cooling of hot lava. It sometimes has holes that once contained volcanic gases.
Obsidian
A black, glassy rock that breaks into pieces with smooth shell-like surfaces
Intrusive Rocks
Igneous rock that forms when magma cools below the Earth’s surface.
Batholith
Intrusive rock mass that measures more than 100 kilometres across.
Granite
A hard, igneous rock with different-coloured crystals large enough to see. It forms slowly below the Earth’s surface.
Sedimentary Rocks
Rocks formed from sediments deposited by water, wind or ice. The sediments are cemented together in layers, under pressure.
Floodplan
Flat, open land beside a river where sediments are deposited during floods
Glaciers
Large bodies of ice that move down slopes and push boulders, rocks and gravel in front of them
Metamorphic rock
Rock formed from another rock that has been under great heat or pressure (or both)
Moraines
Deposit left by movement of a glacier
Sandstone
A sedimentary rock with medium-sized grains. The sand grains are cemented together by silica, lime or other salts.
Mudstone
A fine-grained, sedimentary rock without layering
Shale
A fine-grained sedimentary rock formed in layers by the consolidation of clay.
Siltstone
A sedimentary rock with a particle size between that of sandstone and mudstone.
Conglomerate
Sedimentary rock containing large particles of various sizes cemented together.
Limestone
A sedimentary rock formed from the remains of sea organisms. It consists mainly of calcium carbonate.
Coal
A sedimentary rock formed from dead plants and animals that were buried before rotting completely.
Rock salt
A sedimentary deposit formed when a salt lake or seabed dried up. Its main chemical.
Metamorphism
The process that changes rocks by extreme pressure or heat (or both).
Slate
A fine-grained metamorphic rock formed as a result of moderate heat and pressure on shale.
Marble
A metamorphic rock formed as a result of great pressure on limestone.
Gneiss
A coarse-grained metamorphic rock formed mainly as a result of great pressure on granite.
Mineral Ores
mined to obtain a metal or other chemical within them
Mining
extraction of natural resources from the Earth.
Environmental impact statement
study of the possible effects of a planned project on the environment
Rehabilitated
restored to its previous condition.
Overburden
waste rock removed from below the topsoil. This rock is replaced when the area is restored.
Open-cut mining
mining that scours out soil and rocks on the surface of the land.
Underground mining
mining that uses shafts and tunnels to remove rock from deep below the surface
Stone Age
the time beginning about two million years ago during which early humans made implements of stone
Alloy
A mixture of a metal with a non-metal or another metal
Flint
A fine-grained sedimentary rock which leaves a very sharp edge when broken
Percussion flaking
Aprocess in which tool stones such as flint or obsidian were struck with harder stones, such as quartzite, to shear large flakes that could be used to make small tools
