THE MINERAL SJOGRENITE

Chemistry: Mg₆Fe₂CO₃(OH)₁₆ - 4H₂O, Hydrated Magnesium Iron Carbonate Hydroxide.
Class: Carbonate.
Group: Manasseite.
Uses: Only as mineral specimens.
Specimens

Sjogrenite, which is also spelled sjoegrenite, is a very rare mineral from the famous mines of Langban, Varmland, Sweden. It was discovered there and therefore Langban is called its type locality. Sjogrenite is also found at Sterling Hill, New Jersey; Healdsburg, Sonoma County, California and at Kovdor, Kola Peninsula, Russia.

Sjogrenite is dimorphous with the mineral pyroaurite. Dimorphs are minerals that share the same chemistry but have different structures. Sjogrenite is a hexagonal mineral, while pyroaurite is a trigonal mineral.

PHYSICAL CHARACTERISTICS:

Color is usually white, yellowish, brownish, greenish to off-white.
Luster is vitreous to pearly.
Transparency: Crystals are usually translucent to transparent.
Crystal System is hexagonal; 6/m 2/m 2/m.
Crystal Habits include tabular, scaley to platy crystals; also found in fibrous forms.
Cleavage is perfect in one direction (basal).
Hardness is 2.5.
Specific Gravity is 2.1 (very light).
Streak is white.
Associated Minerals includes tetra-ferriphlogopite, dolomite, pyroaurite, calcite, forsterite, brucite, ludwigite and serpentine.
Notable Occurrences include the type locality of Langban, Varmland, Sweden as well as Sterling Hill, New Jersey; Healdsburg, Sonoma County, California, USA and at Kovdor, Kola Peninsula, Russia.
Best Field Indicators are crystal habits, cleavage, color and locality.