Calcite Powder or Limestone is a common sedimentary rock composed primarily of the calcium carbonate mineral, calcite (CaCO3). Calcite Powder constitutes approximately 10 percent of the sedimentary rocks exposed on the earth surface. Calcite Powder is formed either by direct crystallization from water (usually seawater), or by the accumulation of sea animal shells and shell fragments. In the direct crystallization case calcium ions in the seawater combine with atmospheric or dissolved carbon dioxide to form calcium carbonate, which being insoluble, precipitates out.

Over time, layers of the calcium carbonate form, and with sufficient time and pressure from overlying materials, are transformed to solid rock. The chemical composition of seawater and its minerals contaminants will be recorded in the limestone impurities.

Properties

1. Tactile properties: It is rough and abrasive.

2. Visual properties:

• Color: It is white in color but is also found in various shades like pink, brown etc, depending upon the impurities present. Color is white or none, though shades of gray, red, orange, yellow, green, blue, violet, brown, or even black can occur when the mineral is charged with impurities.
• Luster: Its luster is vitreous to pearly on cleavage surfaces in crystallized varieties and vitreous to resinous to dull in massive forms.
• Streak: Its streak is white.
• Diaphaneity: It is transparent to opaque.

3. Structural properties: It has a defining mohs hardness of 3, a specific gravity of 2.71

4. Combustion properties: It non explosive and non-inflammable.

5. Chemical properties: It dissolves in acids.

6. Affinity to water: Calcite has the ability to adsorb and absorb moisture. However, it has very poor solubility in pure water. In groundwater or rainwater, it can either be dissolved or precipitated depending on several factors including the water temperature, pH, and dissolved ion concentrations. For example, ambient carbon dioxide, due to its acidity, has a slight solubilizing effect on calcite. It exhibits an unusual characteristic called retrograde solubility in which it becomes less soluble in water as the temperature increases. In any case, whether dissolved or suspended, calcite has high dispersibility in water.

7. Affinity to oil: It has low oil absorption capacity.

8. Heat properties:

• Thermal conductivity: 5.526 to 4.646W/(m K) at 273 K
• Specific heat capacity: 0.203 cal/(g K) at 273 K
• Thermal expansion coefficient: 25.8 x 10-6/K to -4.7 x 10-6/K
• Melting point: 1612 K: Decomposition: 850 °C

9. Electric properties: It is poor conductor of electricity.