Aurorite is a rare manganese oxide mineral typically found as earthy or botryoidal coatings in oxidized ore deposits. It is most easily identified by its association with other manganese minerals and its specific occurrence in oxidized mine environments.
Is this aurorite?
5-step field checkRun through these checks against the specimen in your hand. The more boxes tick, the more confident the ID.
- 1Test the hardnessTry to scratch aurorite with a known reference. Aurorite sits at Mohs 1.5 — softer than the next harder reference, harder than the previous one.
- 2Check the streakDrag the specimen across an unglazed porcelain plate. Aurorite leaves a brown streak.
- 3Read the lusterHold the specimen under a strong light. Aurorite typically shows a dull luster.
- 4Match the color rangeCompare against the expected color range: dark brown, black.
- 5Look at form & habitCrystal system: trigonal. Typical habit: massive, earthy, botryoidal crusts.
Often confused with
Aurorite vs. its common look-alikes — and how to tell them apart in the field.
How to tell apart: Streak differs — Aurorite leaves brown, Birnessite leaves brownish-black.
How to tell apart: Romanèchite is the harder of the two (Mohs 5-6 vs. 1.5); streak differs — Aurorite leaves brown, Romanèchite leaves shiny brownish black; luster reads dull on Aurorite and submetallic to dull on Romanèchite.
How to tell apart: Pyrolusite is the harder of the two (Mohs 6-6.5 vs. 1.5); streak differs — Aurorite leaves brown, Pyrolusite leaves black; luster reads dull on Aurorite and metallic on Pyrolusite.
Often found alongside aurorite
Minerals reported to co-occur with aurorite. Spotting these in float or country rock is a strong cue you are in the right ground.
All properties
- Chemical formula
- (Mn²⁺,Ag,Ca,Mn⁴⁺)₇O₁₂·3H₂O
- Mohs hardness
- 1.5
- Density
- 3.2 g/cm³
- Colors
- Streak
- Brown
- Luster
- Dull
- Transparency
- Opaque
- Crystal system
- Trigonal
- Crystal habit
- Massive, Earthy, Botryoidal Crusts
- Cleavage
- None
- Rarity
- Rare
- Uses
- Collector, Scientific Research
- Host rock
- Oxidized Manganese Deposits
- Typical price
- $20-100 per specimen depending on matrix
Where rockhounds find aurorite
Classic worldwide localities
- Aurora mine, Nevada, USA
- Tilly Foster mine, New York, USA
- various manganese deposits
Field-hunting tip
Look in oxidized manganese deposits country — that is the host setting where aurorite typically forms. If you start seeing calcite, quartz, manganese oxides in float, you are in the right ground. Field specimens usually show a massive, earthy, botryoidal crusts habit, so train your eye for that shape before scanning the outcrop.
Common questions
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Find aurorite on the map
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