mineral specimens
rare minerals
mineral dealer
systematic minerals
Black Hills minerals
fine minerals
mineral dealer
Dana minerals
IMA minerals
mineral collections
rock and minerals
gem crystal
0 item @ $0.00  

Strengite with Phosphosiderite

#PD34513

Strengite with Phosphosiderite

#PD34513
Availability
Sold
Size
5.5 x 5 x 3.5 cm - Sm Cabinet 
Formula
Fe3+PO4·2H2O (RRUFF)
Locality
Bull Moose mine, Custer Co., South Dakota, United States
Tagged
phosphate

Strengite and Phosphosiderite are polymorphs- they have the same chemical formula, but belong to different crystal systems. Phosphosiderite is monoclinic, while Strengite is orthorhombic. At the Bull Moose mine, the two are difficult to discern. But careful observation will usually help. The Phosphosiderite are typically more prismatic, showing striation along the c-axis and the terminations will be diamond shaped. Phosphosiderite will also twin (see Jason Smith's photo on Mindat). The best crystals are a raspberry red (see Edgar Müller photo on Mindat). But color is not reliable as Strengite can also be the same color but usually not that red. The Strengite at the Bull Moose are more equant and show some octahedral faces. Saul Krotki's photo on Mindat shows a good distiction between the two. This is not the best specimen, but is a good representative of the Strengite with a little Phosphosiderite. The matrix is dull black Barbosalite with some Pyrite.

Strengite

Formula
Fe3+PO4·2H2
Crystal System
Orthorhombic 
Crystal Habit
Spherical, Radial, Botryoidal 
Cleavage
Good, Poor, None 
Luster
Vitreous (Glassy) 
Color
colorless, pale violet, deep violet, red, carmine red 
Streak
white 
Class
Orthorhombic - Dipyramidal 
Fracture
Brittle - Conchoidal 
Hardness
3.5 

Data courtesy of Webmineral.

Collection
Phillips Collection
Mineralpedia
View Strengite
On Dakota Matrix
Previously Sold Strengite
On Dakota Matrix
Other Available Strengite
WebMineral
View Strengite
Mindat
View Strengite

All photos by Dakota Matrix and are Copyrighted © and may not be used without permission. Copyright © 2020 - Dakota Matrix Minerals, Inc. Privacy | Terms & Conditions | Site Map