Agate
brownwhitegrayblue · Chalcedony family
| Also known as | Chalcedony (Chalcedony family) |
|---|---|
| Colour | Brown, White, Gray, Blue, Red, Clear, Black |
| Mohs hardness | 6.5–7 |
| Lustre | Waxy, vitreous when polished |
| Streak | White |
| Crystal system | Trigonal (quartz) or monoclinic (moganite) |
| Transparency | Transparent to opaque (usually translucent) |
| Cleavage | None |
| Fracture | Conchoidal |
| Chemical formula | SiO 2 (silicon dioxide) |
| Specific gravity | 2.60–2.64 |
What is Agate?
Agate is a banded variety of fibrous chalcedony. Agate stones are characterized by alternating bands of different colored chalcedony and often contain some visible quartz crystals. They are common in nature and can be found globally in a large number of different varieties. Most agates are concentrically banded, while some have bands that form parallel lines. Certain varieties of chalcedony without bands are commonly called agate, but these are not true agates. Moreover, not every banded chalcedony is an agate.
How to identify Agate
- Lustre: Waxy, vitreous when polished.
- Hardness: Mohs 6.5–7 — about as hard as a steel knife.
- Streak: White.
- Habit: Trigonal (quartz) or monoclinic (moganite) crystal system.
Agate in different forms
Stones often confused with Agate
Frequently asked questions
How hard is Agate?
Agate is Mohs 6.5–7 on the hardness scale.
What colour is Agate?
Agate is typically brown, white, gray, blue, red, clear, black (Often multicolored; commonly colorless, pale blue to black, red to orange, yellow, white, brown, pink, purple; rarely gr).