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Sturmanite & Henritermierite

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JYJ1163436

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Description
Locality: 
NChwaning Mines, Kuruman, Northern Cape Province, South Africa
Class: 
Crystals on Matrix
Size Range: 
Miniature (4.5-7 cm)
Size: 
5 × 3 × 2 cm
Description

Bright yellow, glassy sturmanite crystals occur as well-formed rounded to polyhedral aggregates on a pale pink to grey matrix, accompanied by henritermierite from the famous N’Chwaning manganese mines of the Kalahari Manganese Field, South Africa. The sturmanite shows a high vitreous luster and strong color contrast against the fine-grained matrix.

Sturmanite is a rare calcium–iron borate sulfate, first described from this locality, and remains strongly associated with the N’Chwaning mines. Henritermierite, a member of the garnet group, occurs here as granular to crystalline matrix material, providing an excellent paragenetic context typical for this deposit.

This specimen represents a classic Kalahari manganese assemblage, combining rarity, aesthetic crystal form, and a well-documented world-class locality.

Mineral Data
What's on the rock

Sturmanite

Formula: 
Ca6(Fe3+,Al,Mn3+)2(SO4)2[B(OH)4](OH)12·25H2O
Strunz: 
7.DG.15
Crystal System: 
Trigonal
Hardness: 
2.5
Type Locality: 
Black Rock Mine, Black Rock, Kalahari manganese field, Northern Cape Province, South Africa

Henritermierite

Formula: 
Ca3(Mn3+,Al)2(SiO4)2(OH)4
Strunz: 
9.AD.25
Hardness: 
0.0
Streak: 
White
Type Locality: 
Tachgagalt Mine, Ouarzazate Province, Souss-Massa-Draâ Region, Morocco

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Postage Area Price
Germany: Insured parcel 6,20€
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EU insured parcel - 15€
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