Smoky quartz facts for kids
Quick facts for kids Smoky quartz |
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| General | |
| Category | Silicate minerals |
| Formula (repeating unit) |
SiO2 |
| Strunz classification | 04.DA.05 |
| Dana classification | 75.01.03.01 |
| Crystal symmetry | Trigonal 32 |
| Unit cell | a = 4.9133 Å, c = 5.4053 Å; Z=3 |
| Identification | |
| Colour | Brown to grey, opaque |
| Crystal habit | 6-sided prism ending in 6-sided pyramid (typical), drusy, fine-grained to microcrystalline, massive |
| Crystal system | α-quartz: trigonal trapezohedral class 3 2; β-quartz: hexagonal 622 |
| Twinning | Common Dauphine law, Brazil law and Japan law |
| Cleavage | {0110} Indistinct |
| Fracture | Conchoidal |
| Tenacity | Brittle |
| Mohs scale hardness | 7 – lower in impure varieties (defining mineral) |
| Lustre | Vitreous – waxy to dull when massive |
| Streak | White |
| Diaphaneity | Transparent to nearly opaque |
| Specific gravity | 2.65; variable 2.59–2.63 in impure varieties |
| Optical properties | Uniaxial (+) |
| Refractive index | nω = 1.543–1.545 nε = 1.552–1.554 |
| Birefringence | +0.009 (B-G interval) |
| Pleochroism | weak, from red-brown to green-brown |
| Melting point | 1670 °C (β tridymite) 1713 °C (β cristobalite) |
| Solubility | Insoluble at STP; 1 ppmmass at 400 °C and 500 lb/in2 to 2600 ppmmass at 500 °C and 1500 lb/in2 |
| Other characteristics | lattice: hexagonal, Piezoelectric, may be triboluminescent, chiral (hence optically active if not racemic) |
Smoky quartz is a cool type of quartz crystal. It's usually brownish-grey and can be see-through or almost solid. Its color comes from natural radiation in the rocks around it. This radiation changes tiny bits of aluminum inside the quartz, giving it its unique smoky look.
Contents
What is Smoky Quartz?
Smoky quartz is a special kind of quartz mineral. It gets its brownish-grey color from natural radiation. This radiation comes from the surrounding rocks. It activates tiny color centers around aluminum impurities within the quartz crystal. This process makes the crystal change its color.
The color of smoky quartz can range a lot. Some pieces are almost completely clear. Others are a very dark brownish-grey or even black. This makes each piece unique and interesting.
Different Types of Smoky Quartz
There are a few well-known types of smoky quartz. Each one has its own special features.
Morion Quartz
Morion is a very dark type of smoky quartz. It can be so dark that it looks black and isn't see-through. The name "Morion" is used in several languages. These include German, Danish, Spanish, and Polish. It's basically another name for smoky quartz in those places. The name comes from an old writing by Pliny the Elder.
Cairngorm Quartz
Cairngorm is a type of smoky quartz found in Scotland. It comes from the Cairngorm Mountains. This variety usually has a smoky yellow-brown color. Some pieces might be more greyish-brown.
Cairngorm quartz is important in Scottish culture. People use it in jewellery. It also decorates kilt pins. You can even find it on the handles of special Scottish knives called sgian-dubhs. The biggest known Cairngorm crystal is huge. It weighs about 23.6 kilograms (52 pounds). You can see this amazing crystal at Braemar Castle.
How is Smoky Quartz Used?
Smoky quartz is a very common mineral. For a long time, it wasn't considered very important. But recently, it has become a popular gemstone. People love to use it in jewelry because of its unique color.
Smoky quartz has also been used in interesting ways throughout history. For example, in China, people used flat pieces of smoky quartz as Sunglasses way back in the 12th century. This shows how useful and beautiful this crystal can be.
See Also
