- Calcite and dolomite are common carbonate minerals. Calcite is the most widespread mineral near the Earth's surface, with the chemical formula CaCO3. Dolomite has the formula (CaMg)(CO3)2. - Calcite is colorless, white, or grey and has a vitreous luster and perfect rhombohedral cleavage. It reacts quickly with acid to produce bubbles of carbon dioxide. Dolomite is also white but contains magnesium. It reacts more slowly with acid and is slightly harder and denser than calcite. - Both minerals have orthorhombic crystal systems and similar optical properties. Calcite is used as an ornamental stone while

1. Calcite& Dolomite
-Vishnuraayan. G.
12410034

2. Calcite – Introduction
• Most common and widespread mineral on or
near the Earth’s surface.
• Only stable form is CaCO3
• Principal constituent of Sedimentary
limestones
• Occurs in carbonate shells as fine precipitates
and as clastic materials.

3. • Color : Colorless or white, sometimes grey,
yellow, blue, red, brown

4. • Luster : Vitreous
• Diaphaneity : Transparent
to opaque
• Streak : White Streak

5. • Crystal Shape : Triagonal
• Cleavage : Rhombohedral
• Fracture : Conchoidal but rarely visible due to
perfect cleavage
• Hardness : 3.0

6. • Specific Gravity : 2.715(if pure) to 2.94
• Reaction with HCl
powdered + dil. HCl
Brisk effervescence proving presence of
carbonate group

7. Optical Properties
• no = 1.658
• ne = 1.486
• no – ne = 0.172 = δ
• Maximum Birefringence
with fourth order or
higher colors.

8. • Relief : Moderate but large variations are seen
Under PPL Under XPL

9. • Interference Figures
A normal negative uniaxial
interference figure is seen.
• Lamellar Twinning

10. Uses of Calcite
• Many different uses according to its purity and
character.
• Marbles and crystalline limestones –
ornamental stones.
• Calcium Carbonate is used as a flux in smelting
• Certain variety of calcium carbonate is used in
printing
• Lime neutralize the natural acids in the soil.

11. Dolomite – Introduction
• Occurs in extensive beds at many geological
horizons
• Dolomite may be deposited directly from sea
water, but most dolomite beds have been
formed by the alteration of limestones, the
calcite of which is replaced by dolomite.
• Chemical Composition : (CaMg)(CO3)2

12. • Color : White, yellowish, brown, and sometimes
red, green, or black

13. • Luster : Vitreous to
pearly of crystals;
dull of massive
varieties.
• Diaphaneity : Translucent to opaque
• Streak : White
• Crystal Shape : Triagonal
Presence of Mg reduces the symmetry

14. • Cleavage : Rhombohedral
• Fracture : Conchoidal
or Uneven
• Hardness : 3.5 to 4.0
• Specific Gravity : 2.86
• Reaction with HCl
powdered + dil. HCl
Does not rapidly dissolve or effervesce.

15. Optical Properties
• no = 1.679
• ne = 1.500
• no – ne = 0.179 = δ (nearly equal to that of
calcite)
• Maximum Birefringence with fourth order or
higher colors.

16. • Relief : Low to moderate or high
• Interference Figures : A normal negative
uniaxial interference figure is seen.
• Glide Twin lamellae seen on many sections

17. Uses of Dolomite
• Important Building material.
• Making of Refractory furnace lining and
source of carbon dioxide,

18. How do we differentiate
Calcite & Dolomite
• Dolomite differs from calcite because of the
presence of MAGNESIUM.
• Calcite reacts quickly with acids and produce
carbon dioxide bubbles. But dolomite, weakly
reacts with acids producing bubbles very slowly.
• Dolomite is slightly harder and denser than
calcite.
• Calcites form scalenohedrons but dolomites
never form scalenohedrons.

19. Thank You