Hard rock music is an enduringly popular genre, but what is hard rock? Explore the history of hard rock and learn about different hard rock artists.

What type of rock is anthracite coal? Anthracite, also known as "hard coal," is a black, shiny, and hard metamorphic rock formed under intense pressure and temperature. It has the highest fixed ...

Is slate a hard or soft rock? The hardness of slate depends on its individual composition and formation, but this tends to range from 2.5-4 on the Mohs hardness scale.

Chert is a very hard rock (7 on the Mohs Scale). Its color depends on the trace elements that it contains and can be white, green, red, orange, brown, or combinations of them.

Fossil preservation occurs when the minerals in an organism's remains turn to rock or leave an imprint in sedimentary stone. Learn how rapid burial, the organism's hard parts, and the elements ...

Granite is a hard igneous rock with coarse, visible quartz crystal grains. Granite is a rock, which means it is not one mineral but is made up of several minerals.

Limestone is a sedimentary rock. It forms from compaction of components that contain calcium carbonate, cementation of calcium carbonate, or evaporation of water containing calcium carbonate.

Learn about volcanic rock composition and formation. Explore volcanic rock types, including igneous rock, and study examples of the most common volcanic rocks.

Hard coal, or _____, is a lump of high-grade coal having the highest carbon content and fewest impurity. _____ is kept from contaminating buried vegetation through the gradual addition of overburden.

Learn about the evolution of rock band instruments. Discover the core rock and roll instruments and how rock instrumentation progressed throughout history.