Chemical Formula |
CaMg(CO3)2 |
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Composition |
Calcium magnesium carbonate. The amount of calcium and magnesium in most specimens is equal, but occasionally one element may have a slightly greater presence than the other. Small amounts of iron and manganese are sometimes also present. |
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Variable Formula |
(Ca,Mg)2(CO3)2 |
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Color |
Colorless, white, gray, peach, pink, yellow, and orange. Rarely yellow, green, red, and black. |
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Streak |
White |
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Hardness |
3.5 - 4 |
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Crystal System |
Hexagonal |
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3D Crystal Atlas |
|
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Crystal Forms |
Common in groups of small rhombohedral crystals, often with curved, saddle-like faces. Also prismatic, (although usually slightly curved), grainy, botryoidal, coxcomb, and massive. Uncommon in large rhombohedrons or rhombohedral aggregates. |
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Transparency |
Transparent to translucent |
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Specific Gravity |
2.8 - 3.0 |
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Luster |
Vitreous, pearly |
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Cleavage |
1,3 - rhombohedral |
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Fracture |
Conchoidal |
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Tenacity |
Brittle |
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Other ID Marks |
Occasionally fluorescent bluish-white or pink in shortwave ultraviolet light. |
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Complex Tests |
Effervesces in hydrochloric acid. Slowly dissolves in nitric acid and hydrochloric acids. |
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In Group |
Carbonates; |
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Striking Features |
Curved crystals and crystal groupings, associate minerals and environment |
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Environment |
In sedimentary rock such as dolomite rock and limestones. Occasionally in high-temperature metamorphic rocks and low-temperature hydrothermal veins. |
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Rock Type |
Igneous, Sedimentary, Metamorphic |
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Popularity (1-4) |
2 |
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Prevalence (1-3) |
1 |
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Demand (1-3) |
1 |