Mathiasite is a rare titanium-rich mineral member of the crichtonite group typically found within kimberlite pipes. It presents as small, black, opaque crystals that are often difficult to distinguish from other accessory oxides without analytical testing. Collectors generally find these in association with heavy minerals concentrated during diamond mining operations.
Is this mathiasite?
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 mathiasite with a known reference. Mathiasite sits at Mohs 6-7 — softer than the next harder reference, harder than the previous one.
- 2Check the streakDrag the specimen across an unglazed porcelain plate. Mathiasite leaves a brownish black streak.
- 3Read the lusterHold the specimen under a strong light. Mathiasite typically shows a submetallic luster.
- 4Match the color rangeCompare against the expected color range: black.
- 5Look at form & habitCrystal system: trigonal. Typical habit: tabular to rhombohedral crystals.
Often confused with
Mathiasite vs. its common look-alikes — and how to tell them apart in the field.
How to tell apart: Streak differs — Mathiasite leaves brownish black, Manaccanite leaves black.
How to tell apart: Streak differs — Mathiasite leaves brownish black, Chromite leaves dark brown.
How to tell apart: Streak differs — Mathiasite leaves brownish black, Crichtonite leaves black.
Often found alongside mathiasite
Minerals reported to co-occur with mathiasite. Spotting these in float or country rock is a strong cue you are in the right ground.
All properties
- Chemical formula
- (K,Ca,Sr,Ba)(Ti,Cr,Fe,Mg,Zr)₂₁O₃₈
- Mohs hardness
- 6-7
- Density
- 4.67 g/cm³
- Colors
- Streak
- Brownish Black
- Luster
- Submetallic
- Transparency
- Opaque
- Crystal system
- Trigonal
- Crystal habit
- Tabular to Rhombohedral Crystals
- Cleavage
- None
- Rarity
- Rare
- Uses
- Collector
- Host rock
- Kimberlite Pipes
- Typical price
- $50-300 per specimen
Where rockhounds find mathiasite
Classic worldwide localities
- Bultfontein Mine, South Africa
- Khandara, Afghanistan
- Premier Mine, South Africa
Field-hunting tip
Look in kimberlite pipes country — that is the host setting where mathiasite typically forms. If you start seeing diopside, phlogopite, calcite in float, you are in the right ground. Field specimens usually show a tabular to rhombohedral crystals habit, so train your eye for that shape before scanning the outcrop.
Common questions
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Find mathiasite on the map
RockHoundR shows mapped rockhounding spots, access rules, and lets you log every find.
