calcite: Quick Facts

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A photograph of three fragments of calcite made up of one gray cube and two smaller transparent fragments.

calcite crystal structure

Diagram showing several shapes of natural calcite crystals. The top section illustrates four untwinned crystal habits, each with different geometric forms. The bottom section displays two examples of twinned calcite crystals, highlighting how their structures differ. Red dashed lines and axes indicate symmetry and orientation.

Steep white chalk cliffs rise sharply with sparse trees along the top edge on the eastern coast of Mon island, Denmark.

Zincite in white calcite from Franklin, N.J.

Relations between lamellar twinning and cleavage planes in dolomite and calcite. This difference can be discerned best when thin sections of the minerals are viewed under a microscope.

$Diagram of double refraction: an unpolarized light ray enters a transparent calcite crystal and splits into a straight ordinary ray and an upward-bending extraordinary ray.$

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Topics

vaterite calcareous sinter Iceland spar calcium carbonate aragonite calcite group magnesite rhodochrosite siderite smithsonite

Basalt sample returned by Apollo 15, from near a long sinous lunar valley called Hadley Rille. Measured at 3.3 years old.

(Bed) Rocks and (Flint) Stones