Phosphosiderite

Big Photo

Chile
9.02 carats
© Brian Kosnar - Mineral Classics

Phosphosiderite is named after its composition: phosphate and iron (Greek - sideros).

Phosphosiderite forms small crystals up to 2.5 cm or botryoidal masses. The colour is peach-blossom-red, reddish violet, reddish purple, yellow-orange, solid pink, lavender, may be dark blue, moss-green to nearly colourless.

Phosphosiderite is often cut into cabochons.

Phosphosiderite Gemstones by Colour

This table shows the variety of hues this gemstone can be found in. Click on a photo for more information.
 
 

Phosphosiderite Gemstones by Size

This table shows distribution of Phosphosiderite gemstone sizes that are listed on this site. This can give a good indication as to the general availability of this gemstone in different sizes.
Contributed photos
Lightest:7.47 cts
Heaviest:18.50 cts
Average:10.46 cts
Total photos:12
Do you have a larger Phosphosiderite? Why not upload a photo?
7.47ct to 8.57ct8.57ct to 9.68ct9.68ct to 10.78ct10.78ct to 11.88ct11.88ct to 12.99ct12.99ct to 14.09ct14.09ct to 15.19ct15.19ct to 16.29ct16.29ct to 17.40ct17.40ct to 18.50ct
General Information
Chemical Formula
Fe
3+
 
PO
 
4
· 2H
 
2
O
Anthony et al, Handbook of Mineralogy (2001)
Photos of natural/un-cut material from mindat.org
Physical Properties of Phosphosiderite
Mohs Hardness3.5 to 4
Anthony et al, Handbook of Mineralogy (2001)
Specific Gravity2.74 to 2.76
Anthony et al, Handbook of Mineralogy (2001)
Cleavage QualityGood,Indistinct
Anthony et al, Handbook of Mineralogy (2001)
FractureUneven
Anthony et al, Handbook of Mineralogy (2001)
Optical Properties of Phosphosiderite
Refractive Index1.692 to 1.739
Anthony et al, Handbook of Mineralogy (2001)
Optical CharacterBiaxial/-
Anthony et al, Handbook of Mineralogy (2001)
PleochroismPale rose-red - carmine-red - colorless
Anthony et al, Handbook of Mineralogy (2001)
DispersionVery strong
Anthony et al, Handbook of Mineralogy (2001)
Colour
Colour (General)Peach-blossom-red, reddish violet, reddish purple, yellow-orange, may be dark blue, moss-green to nearly colorless; in transmitted light, typically rose-red to colorless.
Anthony et al, Handbook of Mineralogy (2001)
TransparencyTransparent,Translucent
Anthony et al, Handbook of Mineralogy (2001)
LustreVitreous
Anthony et al, Handbook of Mineralogy (2001) Vitreous to subresinous
Crystallography of Phosphosiderite
Crystal SystemMonoclinic
Anthony et al, Handbook of Mineralogy (2001)
HabitAs crystals, tabular, to stout prismatic, many others, to 2.5 cm. May be radial fibrous, in botryoidal or reniform crusts and masses
Anthony et al, Handbook of Mineralogy (2001)
Geological Environment
Where found:Typically an alteration product of triphylite in zoned complex granite pegmatites; may be a component of soils; replacing bones or shells.
Anthony et al, Handbook of Mineralogy (2001)
Further Information
Mineral information:Phosphosiderite information at mindat.org
Significant Gem Localities
USA
 
  • South Dakota
    • Custer Co.
      • Custer Mining District
        • Custer
Copyright © Jolyon & Katya Ralph 1993-2019. Site Map. Locality, gem & photograph data are the copyright of the individuals who submitted them. For more information please contact the . Gemdat.org is an online information resource dedicated to providing free gemmological information to all.