what occurs naturally in small rocks and minerals
Rocks are naturally occurring aggregates of minerals, rock fragments or organic matter. The composition of a rock, as well as the appearance, shape, and arrangement of the grains or crystals within the rock (i.e. its texture), are the characteristics that reveal its process of formation.
A mineral is a naturally occurring chemical compound. Most often, they are crystalline and abiogenic in origin. A mineral is different from a rock, which can be an aggregate of minerals or non-minerals and does not have one specific chemical composition, as a mineral does.