Azoproite is a rare borate mineral belonging to the ludwigite group, typically found in contact-metamorphic skarn deposits. Collectors look for its dark, prismatic or needle-like crystals embedded in crystalline limestone or associated with magnesium-rich silicates.
Is this azoproite?
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 azoproite with a known reference. Azoproite sits at Mohs ~5.5, softer than the next harder reference, harder than the previous one.
- 2Check the streakDrag the specimen across an unglazed porcelain plate. Streak: gray.
- 3Read the lusterHold the specimen under a strong light. Luster: adamantine.
- 4Match the color rangeCompare against the expected color range: black.
- 5Look at form & habitCrystal system: orthorhombic. Typical habit: prismatic to acicular crystals, often as fibrous aggregates.
Often confused with
Azoproite vs. its common look-alikes, and how to tell them apart in the field.
How to tell apart: Streak differs, so Azoproite leaves gray, Ludwigite leaves black to greenish black; luster reads adamantine on Azoproite and submetallic on Ludwigite.
How to tell apart: Streak differs, so Azoproite leaves gray, Vonsenite leaves brownish black; luster reads adamantine on Azoproite and metallic to submetallic, silky if fibrous on Vonsenite.
Often found alongside azoproite
Minerals reported to co-occur with azoproite. Spotting these in float or country rock is a strong cue you are in the right ground.
All properties
- Chemical formula
- Mg₂(Ti₀.₅Mg₀.₅)O₂(BO₃)
- Mohs hardness
- ~5.5
- Density
- 3.63 g/cm³
- Colors
- Streak
- Gray
- Luster
- Adamantine
- Transparency
- Transparent
- Crystal system
- Orthorhombic
- Crystal habit
- Prismatic to acicular crystals, often as fibrous aggregates
- Cleavage
- On {010}, good, may be a parting; on {001}, distinct
- Rarity
- Rare
- Uses
- Collector
- Host rock
- An uncommon late-stage mineral in the border zone in magnesian contact-metamorphic rocks associated with syenites; the deposit is estimated to contain 350 kT B2O3
Where rockhounds find azoproite
Classic worldwide localities
- Tazheran alkalic massif, west of Lake Baikal, eastern Siberia, Russia
Field-hunting tip
Where it forms: An uncommon late-stage mineral in the border zone in magnesian contact-metamorphic rocks associated with syenites; the deposit is estimated to contain 350 kT B2O3. If you start seeing calcite, ludwigite, brucite in float, you are in the right ground. Typical habit: prismatic to acicular crystals, often as fibrous aggregates. Train your eye for that shape before scanning the outcrop.
Common questions
How do you identify azoproite?+
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Find azoproite on the map
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