Arfvedsonite
Arfvedsonite, which is classified as an inosilicate in the amphibole group, is composed of Sodium Iron Magnesium Silicate Hydroxide, and named after the Swedish chemist Johan A. Arfvedson. It is an important constituent in many rocks, and sometimes forms long crystals — these may be prismatic, needle-like, or tabular. It also occurs in fibrous, lamellar, and massive forms, and may be associated with a large number of other minerals, many of which are somewhat obscure. The better known ones include mica, and various kinds of feldspars and feldspathoids. The only use for Arfvedsonite is as mineral specimens.
| Chemical Composition: |
Sodium Iron Maganesium Silicate Hydroxide
Na2(Fe,Mg)4FeSi8O22(OH)2 |
| Color: |
Greenish-black, gray or black |
| Hardness: |
5.5 - 6 |
| Specific Gravity: |
3.1 - 3.5 |
| Cleavage: |
Perfect in two directions |
| Fracture: |
Uneven or sub-conchoidal |
| Crystal Structure: |
Translucent to opaque; monoclinic |
| Luster: |
Vitreous to dull or silky |
| Streak: |
Dark blue gray |
| Occurence: |
Canada, Greenland, Russia, Germany, Norway, USA (Colorado and New Hampshire) |