Eyselite
Eyselite is an IMA-recognized mineral species in the oxides & hydroxide class, with the chemical formula Fe³⁺Ge⁴⁺₃O₇(OH).
It crystallizes in the orthorhombic crystal system.
Key properties: specific gravity 3.639; Browinsh yellow streak; Vitreous luster; optically biaxial.
IMA symbol Eys, IMA status: approved, named in 2003.
A secondary mineral formed by groundwater in a vug on a single specimen of renierite-germanite-tennantite ore from the oxidation zone above a polymetallic sulfide mineral deposit.
It is found associated with Renierite, germanite, tennantite.
The mineral was named to honor Professor Walter Hans Eysel (1935-1999) Professor of Crystallography at the Ruprecht-Karls-Universität, Heidelberg, Germany.
Index entry. This entry combines official IMA/RRUFF species data with published physical-property data — a full written entry hasn’t been published yet.
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