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

Pyroaurite is a rare mineral that comes mostly from the famous mines of Langban, Varmland, Sweden, but is also found at a few other localities. It forms platy to tabular crystals. Crystals of pyroaurite can yield flashes of yellow and it is this display that is responsible for its name; which loosely translated means golden fire. Pyroaurite is dimorphous with the mineral sjogrenite. Dimorphs are minerals that share the same chemistry but have different structures.


  • Color is usually brownish yellow, reddish brown, yellow, white and greenish brown.
  • Luster is vitreous to pearly.
  • Transparency: Crystals are usually translucent to transparent.
  • Crystal System is trigonal; bar 3 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 hydromagnesite, stitchite, calcite, reevesite, sjogrenite, magnetite and lizardite.
  • Notable Occurrences include the type locality of Langban, Varmland, Sweden; Gulsen Quarry, Kraubath, Styria, Austria; Tunnel Hill Quarry, Tasmania, Australia; Sterling Hill, New Jersey; San Francisco County, California, USA; Half-Grunay, Shetland Islands, Scotland; Rutherglan, Ontario and the Parker Mine, Notre Dame du Laus, Quebec, Canada.
  • Best Field Indicators are crystal habits, cleavage, color and locality.
PYROAURITE specimens:
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PYROAURITE specimen pya-1
$ 25.00
Dims: 1.22x0.67x0.71" (3.1x1.7x1.8 cm)
Wt: 0.41 oz. (11.7g)
Langban, Varmland, Sweden
This pyroaurite specimen is from its type locality (Langban). It is perhaps 50% pyroaurite by weight, with most of the rest being calcite and a metal sulfide that I can't identify for certain (it is shiny and almost black, and the only crystal fragment I can see under a loupe looks a lot like magnetite). The pyroaurite is a thick band of an off-white mass of tiny, platy, transparent crystals that have a fairly distinctive reflection pattern under a loupe. The calcite base is noticeably whiter, reflects light differently, and (most distictively) fluoresces a bright orange under short-wave ultraviolet light.
no photo
pya-1 ($ 25.00)
Langban, Varmland, Sweden


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