Amarantite
| Amarantite | |
|---|---|
 | |
| General | |
| Category | Mineral |
| Formula (repeating unit) | Fe3+2[O|(SO4)2]·7H2O |
| Crystal system | triclinic |
| Unit cell | V 674.09 ų (Calculated from Unit Cell) |
| Identification | |
| Color | Amaranth-Red to Brownish Red, Orange-Red |
| Cleavage | Perfect on {010} and {100}, perfect. |
| Tenacity | Brittle |
| Mohs scale hardness | 2½ |
| Luster | Vitreous |
| Streak | Lemon-Yellow |
| Diaphaneity | Transparent |
| Density | 2.189 - 2.286 g/cm3 |
| Pleochroism | Visible |
Amarantite is an amaranth-red to brownish mineral[1] with the general formula of Fe3+2[O|(SO4)2]·7H2O.[2] The name comes from the Greek word αμάραντος which means amaranth, an imaginary undying red flower, in allusion to its color.[3]
Amarantite is triclinic, which means crystallographicaly, it has only one symmetry fold. It must be rotated 360 degrees to be exactly the same. Due to it being triclinic it falls into the biaxial optical class, the axis degrees do not equal 90 degrees and the sides of each axis are not the same length. [4] Amarantite is anisotropic,[1] which means, the velocity of light varies with crystallographic direction, and, thus, there is more than one refractive index.[5]
It has moderate relief[1] is the measure of the relative difference between the index of refraction of the mineral and that of the surrounding medium.[5] Amarantite is a very rare mineral and can only be found in a couple of places such as Carocoles, Chile. [6]
References
- ^ a b c http://www.mindat.org/min-182.html
- ^ Giacovazzo C., Menchetti S. (1968) - Dati strutturali sulla amarantite. Periodico di mineralogia – Roma, pp. 727-731
- ^ Zeitschrift für Kristallographie: 127: 261-275
- ^ Alpers, C.N., Jmbor, J.L., Nordstrom, D.K.(2000) Reviews in Mineralogy and Geochemistry(volume 40) Sulfate Minerals: Crystallography, Geochemisrty, and Environmental Significance
- ^ a b Klein, Cornelis and Cornelius S. Hurlbut, Jr., Marialite-meionite series in Manual of Mineralogy, Wiley, 20th ed. 1985, pp. 287-297.
- ^ http://un2sg4.unige.ch/athena/cgi-bin/minfich?s=Amarantite
- Palache, C., Berman, H., & Frondel, C. (1951), The System of Mineralogy of James Dwight Dana and Edward Salisbury Dana, Yale University 1837-1892, Volume II. John Wiley and Sons, Inc., New York, 7th edition, revised and enlarged, 1124 pp.: 611-613.