Mineral description : Phenakite

Mineral class Silicates : Beryl - tourmaline group
Chemical formula BeCO2SiO4
Crystal system Trigonal / hexagonal
Habitus Short prismatic or romboedric crystals, oftly twinned. Also granular and acicular habits and as radiating fibrous spherulites.
Cleavage Distinct, fracture conchoidal.
Hardness 7.5-8
Density 2.93-3
Color Usually colorless or white, but nuances in yellow, pink and brown exists.
Streak white
Luster Vitreous.
Occurance Forms in hydrothermal veins, granitic igneous rocks and pegmatites. It can also occur in schist with beryl.
Associates In schists : Beryl, chrysoberyl, topaz, quartz, apatite.
In pegmatites : Beryl, bertrandite, euclas, quartz.
Notes Insoluble in acids and infusible.
Locations A rare mineral in Sweden.
  • Långban,Värmland. As up to 8 mm crystals in calcite veins in hematite. Also in tilasite scarn with svabite and romeite.
  • Jakobsbergsgruvan, Nordmark.
  • Selsvitberget, Bollstabruk. Small crystals (<2mm) and masses at the rim of altered beryl.

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Last changed : 1998-03-07