Mineralpedia Details for Allactite
Allactite
Named through the Greek word allasso, meaning “to change,” in reference to Allactite’s strong pleochroism. Allactite is a rare mineral that occurs as a secondary mineral in veins through a metamorphosed manganese deposits at its type locality at the Moss mine in Varmland, Sweden, and also in the metamorphosed zinc orebody at Franklin in New Jersey, USA. Aside from a few other localities in Sweden, Allactite can be found additionally only in Australia at the Iron Monarch mine.
Ref. Handbook of Mineralogy, Anthony et al (1995) and MSA at http://www.handbookofmineralogy.org/pdfs/allactite.pdf
- Formula
- Mn2+7(AsO4)2(OH)8
- Crystal System
- Monoclinic
- Cleavage
- Good, None, None
- Luster
- Vitreous - Greasy
- Color
- brown red, greenish brown, purple red, pink
- Class
- Monoclinic - Prismatic
- Hardness
- 4.5
- WebMineral
- View Allactite
- Mindat
- View Allactite
Allactite from Sterling Hill mine, Ogdensburg, Sussex Co., New Jersey, United States
Excellent reddish crystals on Kraisslite. There are at least four, two are photographed. On the backside are two groups of Chlorophoenicite. Parker label.
Sherry or brownish red micro-crystals to about 1mm as singles and groups of 2 to 5. The crystals are thin tabular with parallel, stepped growth and come to point, but truncated by a pedion. In association with the Allactite is sparse, tiny hexagonal plates of deep blue Covellite and greenish blue, pearly secondary copper mineral perhaps Serpierite.
Allactite from Långban, Filipstad, Värmland, Sweden
Allactite is rare manganese arsenate found in only a handful of worldwide localities including of course Franklin. There are exceptional crystals on this specimen some showing good terminations and prismatic faces.
Allactite from Nordmark, Filipstad, Värmland, Sweden
Hundreds of tiny colorless to faint purple and darker purple micro crystals throughout this matrix.
