Phosphosiderite
| Phosphosiderite | |
|---|---|
 Red phosphosiderite between violet strengite. Picture width 4 mm. | |
| General | |
| Category | Phosphate minerals |
| Formula (repeating unit) | Hydrated iron phosphate FePO4•2H2O |
| IMA symbol | Phsd[1] |
| Crystal system | Monoclinic |
| Crystal class | Prismatic 2/m |
| Space group | P21/n (no. 14) |
| Unit cell | 454.76 ų |
| Identification | |
| Color | Usually red to pink to purple, sometimes green, usually yellow veined |
| Crystal habit | Tabular {010} or stout prismatic [001] |
| Twinning | Common on {101}, typically as interpenetration |
| Cleavage | {010} Distinct, {001} Indistinct |
| Fracture | Uneven |
| Mohs scale hardness | 3.5–4 |
| Luster | Vitreous |
| Streak | White |
| Diaphaneity | Transparent, translucent |
| Specific gravity | 2.74-2.76 |
| Density | 2.74 - 2.76 measured, 2.76 calculated |
| Optical properties | Biaxial (-) |
| Refractive index | nα = 1.692 nβ = 1.725 nγ = 1.738 |
| Birefringence | 0.046 |
| Pleochroism | Visible |
| 2V angle | Measured: 62°, Calculated: 62° |
| Dispersion | r > v, very strong |
| Solubility | Totally soluble in hydrochloric acid, nearly insoluble in nitric acid |
| References | [2] |
Phosphosiderite is a rare mineral named for its main components, phosphate and iron. The siderite at the end of phosphosiderite comes from "sideros", the Greek word for iron.[3] It was discovered in 1890. It is mined in some parts of Chile, Argentina, Germany, Portugal, and the United States.[4][5] It is totally soluble in Hydrochloric acid and nearly insoluble in nitric acid.[6][5] It is usually cut into a cabochon shape.[7]
Colors[]
Phosphosiderite is often found in a bright orchid-purple tint with yellow-colored streaks. The vein-like streaks found in the stone are known as cacoxenite. Four other rare color variants are rose red, brown-reddish yellow, mossy green, and dark shades of purple. Phosphosiderite can also be found as a colorless mineral.[8] It is pleochroic; on the X axis around 4° it is light rose, on the Y axis it is carmine red, and on Z it is colorless.[8]
References[]
- ^ Warr, L.N. (2021). "IMA–CNMNC approved mineral symbols". Mineralogical Magazine. 85: 291–320.
- ^ Taxer, K.; Bartl, H. (December 2004). "On the dimorphy between the variscite and clinovariscite group: refined finestructural relationship of strengite and clinostrengite, Fe(PO4). 2H2O". Crystal Research and Technology. 39 (12): 1080–1088. doi:10.1002/crat.200410293.
- ^ "siderite". Oxford English Dictionary (Online ed.). Oxford University Press. (Subscription or participating institution membership required.)
- ^ Minerals, Dakota Matrix. "Phosphosiderite mineral information and data". www.dakotamatrix.com. Retrieved 2021-04-30.
- ^ a b Anthony et al, Handbook of Mineralogy (2001)
- ^ "Phosphosiderite". National Gem Lab. 18 March 2017.
- ^ "Phosphosiderite gemstone information". www.gemdat.org. Retrieved 2020-09-14.
- ^ a b "Phosphosiderite". www.mindat.org. Retrieved 2021-03-05.
- Monoclinic minerals
- Minerals in space group 14