AllMineralsRock
Calcite Vs. Gypsum
Calcite is a very popular mineral composed of calcium carbonate.[1] Gypsum is also a very popular mineral and its chemical composition is calcium sulfate.[2]
Quick Facts on Differences of Calcite and Gypsum
For a quick recap of the differences calcite and gypsum:- In terms of crystallography, calcite can be hexagonal or trigonal while gypsum is monoclinic.
- For chemical formulas, calcite is CaCO3 while gypsum is CaSO4· 2H2O.
- While both calcite and gypsum can be commonly red, gypsum is often brown or yellow.
- Calcite's hardness is higher than gypsum - calcite is 3 and gypsum ranges from 1.5 to 2 on the Moh's scale.
- Calcite's specific gravity is higher than gypsum - calcite ranges from 2.71 to 2.94 and gypsum ranges from 2.3 to 2.32.
Quick Facts on Similarities of Calcite and Gypsum
The similarities of calcite and gypsum include:- Calcite and gypsum both can be opaque, translucent or transparent.
- In terms of luster, calcite and gypsum both can be pearly or vitreous.
- Calcite and gypsum both streak white.
- Calcite's rarity is similar to gypsum.
Summary of Calcite
Calcite is a mineral that is widely distributed throughout the world. It is a carbonate mineral that is composed of calcium carbonate, which gives it a white or colorless appearance. Calcite is often found in sedimentary rocks, such as limestone and marble, as well as in hydrothermal veins and in some metamorphic rocks. It is also found in the shells of marine organisms, such as clams and oysters.Summary of Gypsum
Gypsum is a soft, white or gray mineral that belongs to the sulfate mineral family. It is composed of calcium sulfate dihydrate (CaSO4·2H2O) and is commonly found in sedimentary rocks. Gypsum is often found in thick beds or layers, and its crystals are usually flat and elongated. It has a hardness of 2 on the Mohs scale and a specific gravity of 2.3. One of the unique properties of gypsum is that it loses water when heated, which makes it an excellent material for making plaster.Table Comparison of Calcite vs Gypsum
| Calcite (src) | Gypsum (src) | |
|---|---|---|
| Transparency | transparent, translucent, opaque | transparent, translucent, opaque |
| Chemical Formula | CaCO3 | CaSO4· 2H2O |
| Chemical Composition | calcium carbonate | calcium sulfate |
| Specific Gravity | 2.71, 2.94 | 2.3, 2.32, 2.33 |
| Hardness | 3 | 1.5, 2 |
| Streak | white | white |
| Crystallography | hexagonal, trigonal | monoclinic |
| Refractive Index | 1.486, 1.74 | 1.52, 1.53 |
| Hydrous | No | Yes |
| Colors | common: red sometimes: pink, purple, colorless less common: blue, gray, black, brown, green, white, orange, yellow, multicolor |
common: brown, red, yellow sometimes: blue, green, white, orange less common: tan, gray, pink, beige, black, colorless, band |
| Solubility | Soluble in dilute acids | Soluble in dilute HCl |
| Category | carbonate | sulfate |
| Birefringence | δ = 0.154–0.174 | δ = 0.010 |
| Fracture | conchoidal | uneven |