Polyadelphite
A variety of Andradite
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About Polyadelphite
Formula:
(Ca,Mn)3Fe3+2(SiO4)3
Colour:
Brown, red-brown, orange-brown, brown-black
Lustre:
Vitreous, Sub-Vitreous, Resinous
Hardness:
6½ - 7
Specific Gravity:
3.8 - 3.9
Crystal System:
Isometric
Name:
Named in 1836 by Thomas Thomson from the Greek πολλές "many" and αδελφός "brother" in allusion to the great variety of elements in the chemical analyses.
First Recorded Locality:
A red-brown, golden brown, or yellow-brown variety of Mn-bearing andradite.
Unique Identifiers
Mindat ID:
9396 (as Polyadelphite)
223 (as Andradite)
223 (as Andradite)
Long-form identifier:
mindat:1:1:9396:1 (as Polyadelphite)
mindat:1:1:223:5 (as Andradite)
mindat:1:1:223:5 (as Andradite)
Similar Names
| Polyadelphine | A synonym of Andradite |
IMA Classification of Polyadelphite
First published:
1836
First description reference:
Physical Properties of Polyadelphite
Vitreous, Sub-Vitreous, Resinous
Transparency:
Transparent, Translucent
Colour:
Brown, red-brown, orange-brown, brown-black
Streak:
White
Hardness:
6½ - 7 on Mohs scale
Hardness Data:
Measured
Tenacity:
Brittle
Cleavage:
None Observed
Parting:
Poor to good parting is frequently observed
Fracture:
Irregular/Uneven, Sub-Conchoidal
Density:
3.8 - 3.9 g/cm3 (Measured)
Chemistry of Polyadelphite
Mindat Formula:
(Ca,Mn)3Fe3+2(SiO4)3
Element Weights:
Crystallography of Polyadelphite
Crystal System:
Isometric
Class (H-M):
m3m (4/m 3 2/m) - Hexoctahedral
Morphology:
Dodecahedral crystals with trapezohedral modifications
First Recorded Occurrence of Polyadelphite
General Appearance of First Recorded Material:
Dark brown crystals and masses
Geological Setting of First Recorded Material:
Polymetallic sulphide-poor zinc deposit
Associated Minerals at First Recorded Locality:
Common Associates
Associations Based on Photo Data:
| 3 photos of Polyadelphite associated with Hendricksite | KZn3(Si3Al)O10(OH)2 |
| 2 photos of Polyadelphite associated with Franklinite | Zn2+Fe3+2O4 |
| 2 photos of Polyadelphite associated with Willemite | Zn2SiO4 |
| 2 photos of Polyadelphite associated with Calcite | CaCO3 |
| 1 photo of Polyadelphite associated with Rhodonite | CaMn3Mn[Si5O15] |
Fluorescence of Polyadelphite
Not fluorescent
Other Information
Health Risks:
No information on health risks for this material has been entered into the database. You should always treat mineral specimens with care.
Internet Links for Polyadelphite
mindat.org URL:
https://www.mindat.org/min-9396.html
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References for Polyadelphite
Localities for Polyadelphite
Showing 2 localities.
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The Locality List
- This locality has map coordinates listed.
- This locality has estimated coordinates.
ⓘ - Click for references and further information on this occurrence.
? - Indicates mineral may be doubtful at this locality.
- Good crystals or important locality for species.
- World class for species or very significant.
(TL) - Type Locality for a valid mineral species.
(FRL) - First Recorded Locality for everything else (eg varieties).
All localities listed without proper references should be considered as questionable.
USA (FRL) | |
| Thomas Thomson (1836) |
| King (n.d.) |
Sterling Mine, Sterling Hill, Ogdensburg, Sussex County, New Jersey, USA