Lyonsite

lyonsite

thenardite

howardevansite

vanadium

Images

Formula: Cu2+3Fe3+4(VO4)6
Anhydrous vanadate
Crystal System: Orthorhombic
Specific gravity: 4.215 calculated
Streak: Dark grey
Colour: Black
Environments

Fumeroles

Localities

At the type locality, the Izalco Volcano, Sonsonate Department, El Salvador, lyonsite has been discovered in the summit crater fumaroles. The mineral, which occurs with thénardite and howardevansite, formed as a sublimate product from the volcanic gases at up to 800oC. Lyonsite occurs as euhedral, black lathlike crystals up to 230 microns in greatest dimension (AM 72.1000-1005, HOM).
Lyonsite from the Izalco Volcano - Image

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