Réf : BH611

Minéral d'aegirine cristallisée noire sur Orthose du Malawi

Aegirine on Orthossa - Malawi - crystalline minerals 6.4 cm / 210g / BH611 - Vignette | 1001 minéraux

Aegirine on Orthossa - Malawi - crystalline minerals 6.4 cm / 210g / BH611

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GIRINE belongs to the silicate group. It contains sodium, iron, and silicon. It is a sodium iron silicate. Its chemical formula is NaFe(Si3O6).
The Æ GIRINE generally presents prismatic or acicular striated and shiny crystals.
The color of Æ GIRINE is most often black, but brown or green Æ girine crystals are also found.
The density of Æ girine is greater than 3.5 (1 for water) and its hardness is 6/10 on the Mohs scale (10 for diamond). The streak on the porcelain is predominantly green.
The name Æ girine comes from the name of the Scandinavian mythological god Æ gir.

Orthoclase belongs to the silicate group, tectosilicate subgroup. Its chemical composition is KAlSi3O8.
Orthoclase is a very common potassium feldspar with the same chemical formula as Microcline (Amazonite), but which exhibits multiple twinning.
Its color varies from white to gray, yellow, red, pink, green, and can even be colorless. Its density is greater than 2.5 (1 for water) and its hardness is greater than 6/10 on the Mohs scale (10 for diamond). The streak color on porcelain is white. Orthoclase can be polished into freeform shapes, pebbles, or tumbled stones.
Inspired by the ability of Orthoclase to cleave along two orthogonal planes, its name was found by the mineralogist Johann August Friedrich Breithaupt who gave it to it in 1823, a word derived from the Greek orthos which means straight.