Definitions
Any trace left in rock by a plant or animal
Fossil
Any hollow space in the earth's crust that has formed naturally and is large enough for a person to enter
Cave
A rough, crumbly sedimentary rock which consists of particles of quartz sand that have been fused together into rock; sometimes used to make glass
Sandstone
What rock is formed from sediments that have been pressed together into rock?
Sedimentary
A rock produced by metamorphism of an igneous or sedimentary rock
Metamorphic rock
The hard material that composes the earth's crust
Rock
A sedimentary rock formed from mud or clay that consists of much smaller particles than sand
Shale
What type of rock forms when molten rock solidifies either above or below ground?
Igneous rock
The reddish-orange metal that covers a penny and is a good conductor of electricity
Copper
The individual substances that make up rocks
Minerals
A chemical substance made primarily of hydrogen and carbon
Hydrocarbon
A shiny, black rock that resembles glass
Obsidian
What useful fuel, commonly found in sedimentary rock, comes from decayed plants and is used for heating, industrial purposes, and generating electricity?
Coal
A hard, crystalline form of carbon that is the hardest of all known minerals
Diamond
The rarest, most durable and beautiful gems
Precious stones
"rock oil"; a liquid fossil fuel that may have been formed from the remains of once-living creatures
Petroleum
A strong, light-colored igneous rock that contains at least three different kinds of mineral crystals; the most common igneous rock
Granite
What strong, practical metal is the most commonly used metal?
Iron
The most common type of organic sedimentary rock, made from calcium carbonate
Limestone
Small deposits of igneous and metamorphic crystals in rock
Gemstones
A fuel derived from the remains of plants or animals
Fossil fuel
A sedimentary rock made of rounded pebbles embedded in hardened sand or clay
Conglomerate
What is the hard, shiny, black coal that is the most expensive to mine?
Anthracite coal
The most common type of coal, also called soft coal, is widely used by industry and used to produce electricity in power plants
Bituminous coal