AllMineralsRock
Prehnite Vs. Quartz
Prehnite is a popular gemstone composed of calcium aluminum silicate.[1] Quartz is a very popular gemstone and its chemical composition is silicon dioxide.[2]
Quick Facts on Differences of Prehnite and Quartz
For a quick recap of the differences prehnite and quartz:- While both prehnite and quartz can be translucent or transparent, quartz can be opaque.
- In terms of crystallography, prehnite is orthorhombic while quartz can be hexagonal or trigonal.
- For chemical formulas, prehnite is Ca2Al2Si3O12(OH) while quartz is SiO2.
- While both prehnite and quartz can be vitreous or waxy, in terms of luster, prehnite can be pearly and quartz can be greasy.
- While both prehnite and quartz can be commonly yellow, prehnite is often green and quartz is often red.
- Prehnite's rarity is more rare than quartz.
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Prehnite's hardness is lower than quartz - prehnite ranges from 6 to 6.5 and quartz is 7 on the Moh's scale.
- Prehnite can be scratched by quartz (7) while quartz can not be.
Quick Facts on Similarities of Prehnite and Quartz
The similarities of prehnite and quartz include:- Prehnite and quartz both streak white.
- Prehnite's specific gravity overlaps with quartz - prehnite ranges from 2.8 to 2.88 and quartz ranges from 2.651 to 2.91.
Summary of Prehnite
Prehnite is a silicate mineral that is typically found in basaltic rocks and hydrothermal veins. It was first discovered in South Africa in 1788 and was named after the Dutch mineralogist, Colonel Hendrik von Prehn. Prehnite is a translucent to transparent mineral that can range in color from pale green to yellow, gray, or white. It is often found in aggregates or as crusts on other minerals.Summary of Quartz
Quartz is a mineral that is composed of silicon and oxygen atoms arranged in a continuous framework of SiO4 silicon-oxygen tetrahedra. It is one of the most abundant minerals found in the Earth's crust. Quartz can be found in a variety of colors such as white, pink, purple, brown, gray, and black. It is also known for its unique crystal structure, which is hexagonal in shape, and its hardness, which is 7 on the Mohs scale.Table Comparison of Prehnite vs Quartz
| Prehnite (src) | Quartz (src) | |
|---|---|---|
| Transparency | transparent, translucent | transparent, translucent, opaque |
| Chemical Formula | Ca2Al2Si3O12(OH) | SiO2 |
| Chemical Composition | calcium aluminum silicate | silicon dioxide |
| Specific Gravity | 2.8, 2.88, 2.94, 3 | 2.651, 2.91 |
| Hardness | 6, 6.5 | 7 |
| Streak | white | white |
| Crystallography | orthorhombic | hexagonal, trigonal |
| Refractive Index | 1.611, 1.665 | 1.544, 1.553 |
| Hydrous | No | No |
| Colors | common: green, yellow sometimes: gray less common: pale, white, colorless |
common: red, yellow sometimes: blue, gray, pink, black, brown, green, white, orange, purple, violet, colorless, multicolor |
| Category | silicate | silicate |
| Birefringence | δ = 0.021 - 0.033 | δ = +0.009 (B-G interval) |
| Fracture | uneven | conchoidal, uneven |