煙水晶
Smoky quartz is the grey-to-brown variety of quartz, coloured by natural irradiation; the darkest form is called cairngorm.
基本資料
| 化學式 | SiO2 |
|---|---|
| IMA 代號 | Qz |
| 施特龍茨分類 | 9.A |
| 晶系 | 三方晶系 |
| 點群 | 32 |
| 稀有度 | 常見 |
| 收藏級別 | 適合陳列 |
| 變種來源 | 石英 |
| 模式產地 | —, — |
Smoky quartz is the smoky grey, brown or near-black variety of crystalline quartz. Its colour is produced by natural radiation acting on tiny amounts of aluminium in the quartz structure, which is why it is common in granites and pegmatites containing trace radioactive elements.
Identifying smoky quartz
Like all quartz it is hard (7) and forms six-sided prisms with pyramidal terminations; colour ranges from a pale smoky tint to deep brown-black (the very dark Scottish form is called cairngorm). Colour is often uneven and concentrated toward the tips. Some pale material on the market is irradiated to deepen the colour.
Where it is found
Smoky quartz is found worldwide — fine crystals come from the Swiss and Austrian Alps, Brazil, the Pikes Peak granite of Colorado (with amazonite), Scotland and many granite and pegmatite districts.
For collectors
Sharp, lustrous crystals with rich even colour and clean terminations are the most desirable, especially the classic amazonite–smoky quartz combinations.
