Rocks, Minerals & Ores
Mineral Sequence in the Cady Mountains
Calcite scalenohedron twin
CaCO3Cady Mountains, Mojave Desert, CA
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Mineral Sequence in the Cady Mountains
A twin is a symmetrical intergrowth of at least two crystals of the same mineral. The individuals of the twinning are related by a symmetric element which is absent in the untwinned crystal. Twins can be contact twins, penetration twins and polysynthetic twins (or mechanical twins). In a contact twin (or twin by reflection) there is definite surface (plane) separating the two individuals. In a penetration twin, very often the individuals are joined along an irregular surface.
Calcite.be