General Information

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General Info Page:

Formula: CaCO₃

Names: calcium carbonate, limestone (and marble), chalk, calcite

Molar Mass: 100.1 g

Percent Composition by Mass: Ca= 40.1 %, C = 12.0%, O= 48.0 %

Percent Composition by Number: Ca=20%, C= 20%, O = 60%

Bond Type: ionic- Ca²⁺ ions and CO₃^2-  ions join to form crystals 

Crystal Type: usually rhombohedra because of cleavage properties.

Cleavage: perfect in three directions

Melting Point: 826 degrees C

Color: usually white or transparent but comes in a variety of colors including yellow, pink and gray

Density: 2.7

Hardness: 3 (on Moh’s scale)

Other properties: can be florescent. Other variations of calcite crystals can also be phosphorescent (meaning they glow after the ultra-violet light that passed through has left because its electrons obtain the light’s energy), thermoluminescence (meaning it glows when heated), and a more unusual property of triboluminescence (meaning it glows when crushed, scratched, struck, or rubbed).