Phosphosiderite
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Phosphosiderite is named after its chemical composition, PHOSPHrous and the Greek word SIDERos for Iron.

Discovered in 1890; IMA status: Valid (pre-IMA; Grandfathered)

Chemistry

Chemical Formula:

FePO₄ • 2(H₂O)

Hydrated Iron Phosphate

Molecular Weight:

186.85 gm

Composition:

Iron

29.89 %

Fe

42.73 %

Fe₂O₃

Phosphorus

16.58 %

P

37.98 %

P₂O₅

Hydrogen

2.16 %

H

19.28 %

H₂O

Oxygen

51.38 %

O

100.00 %

100.00 %

= TOTAL OXIDE

Classification

Mineral Classification:

Phosphates

Strunz 8th Ed. ID:

7/C.09-20

Nickel-Strunz 10th Ed. ID:

8.CD.05

8 : PHOSPHATES, ARSENATES, VANADATES
C : Phosphates without additional anions, with H₂O
D : With only medium-sized cations, RO₄:H₂O = 1:2

Related to:

Metavariscite Group. Dimorphous with Strengite.

Members of Group:

Metavariscite Group: Kolbeckite, Metavariscite, Phosphosiderite

Varieties:

Vilateite

Synonyms:

Clinobarrandite, Clinostrengite, Metastrengite

Crystal Data

Crystallography:

Monoclinic - Prismatic

Crystal Habit:

Crystals tabular {010} or stout prismatic [001]. Also occurs as botryoidal or reniform masses and crusts with a radial-fibrous structure.

Twinning:

On {101}, common, typically as interpenetrations

Physical Properties

Cleavage:

Distinc/good on {010}, Indistinct on {001}

Fracture:

Irregular/Uneven

Tenacity:

Brittle

Moh's Hardness:

3.5 - 4.0

Density:

2.74 - 2.76 (g/cm³)

Luminescence:

None

Radioactivity:

Not Radioactive

Other:

Totally soluble in HCl, nearly insoluble in HNO3

Optical Properties

Color:

Colorless, purple, pink, red, red violet

Transparency:

Transparent to Translucent, Opaque

Luster:

Vitreous to Sub-Resinous

Refractive Index:

1.692 - 1.738  Biaxial ( - )

Birefringence:

0.046

Dispersion:

Very strong; r > v

Pleochroism:

Visible; X = pale rose-red; Y = carmine-red; Z = colorless

Occurances

Geological Setting:

Typically an alteration product of triphylite in zoned complex granite pegmatites; may be a component of soils; replacing bones or shells.

Common Associations:

Triphylite, Barbosalite, Leucophosphite, Laueite, Huréaulite, Strengite, Turquoise

Common Impurities:

Al, Mn

Type Locality:

Kalterborn Mine, Eiserfeld, Siegerland, North Rhine-Westphalia, Germany

Year Discovered:

1890

View mineral photos:

Phosphosiderite Mineral Photos and Locations

More Information

Mindat.org
Webmineral.com

Phosphosiderite is a rare mineral found as minute crystals of pink or red. It is also found as massive or botryoidal forms suitable for cabochons. Phosphosiderite is similar in appearance to Sugilite. The pink, opaque massive material is currently being mined in Chile. This material is either solid pink, lavender or purple and may have yellow veins. It is also known as "piedrea voga" (pink stone) as well as "la rosa voca" (pink rock).
 

  
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