Olkhonskite is a very rare vanadium-titanium oxide mineral discovered in the metasomatic rocks of Olkhon Island. It typically occurs as microscopic yellow to brownish-black crusts or aggregates, making it primarily a species for specialized mineral collectors.
Is this olkhonskite?
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 olkhonskite with a known reference. Olkhonskite sits at Mohs 8, softer than the next harder reference, harder than the previous one.
- 2Check the streakDrag the specimen across an unglazed porcelain plate. Streak: black.
- 3Read the lusterHold the specimen under a strong light. Luster: metallic.
- 4Match the color rangeCompare against the expected color range: black.
- 5Look at form & habitCrystal system: monoclinic. Typical habit: disseminated, platy.
Often confused with
Olkhonskite vs. its common look-alikes, and how to tell them apart in the field.
How to tell apart: Olkhonskite is noticeably harder (Mohs 8 vs. 5.5-6.5); luster reads metallic on Olkhonskite and submetallic on Montroseite.
How to tell apart: Olkhonskite is noticeably harder (Mohs 8 vs. 4-5); luster reads metallic on Olkhonskite and submetallic on Paramontroseite.
Often found alongside olkhonskite
Minerals reported to co-occur with olkhonskite. Spotting these in float or country rock is a strong cue you are in the right ground.
All properties
- Chemical formula
- Cr₂Ti₃O₉
- Mohs hardness
- 8
- Density
- 4.48 g/cm³
- Colors
- Streak
- Black
- Luster
- Metallic
- Transparency
- Opaque
- Crystal system
- Monoclinic
- Crystal habit
- Disseminated, platy
- Cleavage
- None
- Rarity
- Rare
- Uses
- Collector
- Host rock
- In quartzite schists, enriched in Cr–V–Ti, interbedded with carbonate-silicate rocks
Where rockhounds find olkhonskite
Classic worldwide localities
- On the western shore of Lake Baikal, 4.5 km south of the Olkhon Island, Russia (type locality)
Field-hunting tip
Where it forms: In quartzite schists, enriched in Cr–V–Ti, interbedded with carbonate-silicate rocks. If you start seeing rutile, eskolaite, karelianite in float, you are in the right ground. Typical habit: disseminated, platy. Train your eye for that shape before scanning the outcrop.
Common questions
How do you identify olkhonskite?+
Where is olkhonskite found?+
Is olkhonskite safe to handle?+
What rocks look like olkhonskite?+
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Find olkhonskite on the map
RockHoundR shows mapped rockhounding spots, access rules, and lets you log every find.
