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minerals that contain combinations of carbon and oxygen in their chemical structure.


the tendency of a mineral to break along preferred planes

conchoidal fracture

A broken surface with concentric, raised surface markings looking similar to the ridges on a seashell (see also fracture).


a rock formed by the solidification of a substance

crystal face

the flat surface of an euhedral mineral grain

crystal habit

the general shape of a crystal or cluster of crystals that grew unimpeded

crystal lattice

the orderly framework within which the atoms or ions within a crystal

crystal structure

the internal arrangement of atoms or ions within a crystal


a smooth surface (as of a bone or cut gemstone)


art highly prized for its beauty or perfection


(mineralogy) a hollow rock or nodule with the cavity usually lined with crystals


a measure of how easily a mineral can be scratched


the visual property of something that shines with reflected light


solid homogeneous inorganic substances occurring in nature having a definite chemical composition


the branch of geology that studies minerals: their structure and properties and the ways of distinguishing them

Mohs hardness scale

a scale ranking ten minerals from softest to hardest; used in testing the hardness of minerals


One of two or more alternative possible crystal structures for a single chemical compound; for example, the minerals quartz and cristobalite are polymorphs of silica (SiO2).

silicate mineral

a mineral that contains a combination of silicon, oxygen, and one or more metals

silicon-oxygen tetrahedron

the basic unit of the structure of silicate minerals; a silicon ion chemically bonded to and surrounded by four oxygen ions

specific gravity

the density of a substance relative to the density of water


a marking of a different color or texture from the background


having the same shape, size, and position on both sides of a dividing line

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