Howardevansite

howardevansite

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Formula: NaCu2+Fe3+2(VO4)3
Anhydrous vanadate, howardevansite group
Crystal System: Triclinic
Specific gravity: 3.814 calculated
Streak: Red-brown
Colour: Black
Common impurities: Al,Mn,Ti
Environments

fumeroles

Although howardevansite was approved in 1987, to date (April 2025) it has been reported only from the type locality.

Localities

The type locality, the Izalco Volcano, Sonsonate Department, El Salvador, is a Holocene (11,700 years ago until the present) basalt-andesite volcano that has been intermittently active since its formation in 1770. The fumaroles of the volcano have been a rich source of high-temperature vanadium minerals. The minerals form as sublimates from a vanadium halogen or oxyhalogen gas that was exsolved from a basaltic magma when the magma was 550 m below the summit crater; at the fumaroles, the vanadium compounds sublimed at temperatures up to 800oC.
Howardevansite has been discovered in the summit crater fumaroles, occuring with lyonsite and thénardite, formed as sublimates from the volcanic gases. Howardevansite occurs as euhedral, black tabular crystals; hundreds of crystals are available, all less than 100 microns in greatest dimension (AM 73.181-186).
Howardevansite from the Izalco Volcano - Image

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