Jasper
redbrowngreen · Chalcedony family
| Also known as | Chalcedony (Chalcedony family) |
|---|---|
| Colour | Red, Brown, Green, Yellow |
| Mohs hardness | 6.5–7 |
| Lustre | Vitreous |
| Streak | White |
| Crystal system | Hexagonal |
| Transparency | Opaque |
| Cleavage | none |
| Fracture | Conchoidal |
| Chemical formula | SiO 2 (with varying impurities) |
| Specific gravity | 2.5–2.9 |
What is Jasper?
Jasper, an aggregate of microgranular quartz and/or cryptocrystalline chalcedony and other mineral phases, is an opaque, impure variety of silica, usually red, yellow, brown or green in color; and rarely blue. The common red color is due to iron(III) inclusions. Jasper breaks with a smooth surface and is used for ornamentation or as a gemstone. It can be highly polished and is used for items such as vases, seals, and snuff boxes. The density of jasper is typically 2.5 to 2.9 g/cm3. Jaspillite is a banded-iron-formation rock that often has distinctive bands of jasper.
How to identify Jasper
- Lustre: Vitreous.
- Hardness: Mohs 6.5–7 — about as hard as a steel knife.
- Streak: White.
- Habit: Hexagonal crystal system.
Jasper in different forms
Stones often confused with Jasper
Frequently asked questions
How hard is Jasper?
Jasper is Mohs 6.5–7 on the hardness scale.
What colour is Jasper?
Jasper is typically red, brown, green, yellow (Most commonly red, but may be yellow, brown, green or (rarely) blue).