Riebeckite facts for kids
Quick facts for kids Riebeckite |
|
|---|---|
.jpg)
Black riebeckite in an alkaline pegmatite from Lindinosa near Évisa, Corsica, France
|
|
| General | |
| Category | Silicate mineral |
| Formula (repeating unit) |
☐Na2(Fe2+3Fe3+2)Si8O22(OH)2 |
| Crystal symmetry | Monoclinic 2/m |
| Unit cell | a = 9.76 Å, b = 18.04 Å, c = 5.33 Å; β = 103.59°; Z=2 |
| Identification | |
| Color | Black, dark blue; dark blue to yellow-green in thin section |
| Crystal habit | As prismatic crystals, commonly fibrous, asbestiform; earthy, massive |
| Crystal system | Monoclinic - Prismatic |
| Twinning | Simple or multiple twinning parallel to {100} |
| Cleavage | Perfect on {110}, intersecting at 56° and 124°; partings on {100} and {010} |
| Fracture | Conchoidal to uneven |
| Tenacity | Brittle |
| Mohs scale hardness | 6 |
| Luster | Vitreous to silky |
| Streak | Pale to bluish gray |
| Diaphaneity | Semitransparent |
| Specific gravity | 3.28–3.44 |
| Optical properties | Biaxial (-) |
| Refractive index | nα = 1.680–1.698 nβ = 1.683–1.700 nγ = 1.685–1.706 |
| Birefringence | δ = 0.005–0.008 |
| Pleochroism | X = blue, indigo; Y = yellowish green, yellow brown; Z = dark blue |
| 2V angle | Measured: 68° to 85°, Calculated: 62° to 78° |
| Dispersion | Strong |
Riebeckite is a type of mineral found in rocks. It belongs to a group of minerals called silicates, which are very common on Earth. Riebeckite can look different depending on how it forms. It can be found as solid crystals or as tiny, hair-like fibers.
Contents
What is Riebeckite?
Riebeckite is a mineral that forms in certain types of rocks. It is part of the amphibole group of minerals. Its chemical formula shows it contains sodium, iron, silicon, oxygen, and hydrogen. This mineral often appears black or dark blue.
Different Forms of Riebeckite
Riebeckite comes in two main forms:
- Solid Form: This form looks like regular crystals. It can be found in rocks like granite.
- Fibrous Form: This form is made of very thin, flexible fibers. It is also known as blue asbestos or crocidolite asbestos.
Blue Asbestos: A Special Form
Blue asbestos is one of the six types of asbestos. Asbestos is a natural material that was once used a lot because it resists heat and fire. However, blue asbestos is known to be the most risky type of asbestos.
Why Blue Asbestos is Dangerous
When blue asbestos fibers are in the air, they can be breathed in. These tiny fibers can get stuck in the lungs. Over time, this can lead to serious health problems. These problems include a lung disease called asbestosis and certain types of cancer.
Past Uses of Blue Asbestos
Because of its heat-resistant qualities, blue asbestos was used in some products in the past. For example, it was once used as a filter material in certain cigarette brands. It was also sometimes found in building materials like caulking, cement, and wallboard. However, it was much less common than other types of asbestos, like white asbestos.
Why it is No Longer Mined
Due to the serious health risks, blue asbestos is no longer dug out of the ground for commercial use. Governments and health organizations worldwide have put rules in place to protect people from asbestos.
Related pages
Images for kids
-
Crocidolite, variety of riebeckite, from Pomfret Mine, Vryburg, South Africa
.jpg)
See also
In Spanish: Riebeckita para niños
