Bustamite is a manganese calcium silicate often found in metamorphic manganese deposits. It is most frequently encountered as massive, fibrous, or granular material rather than well-defined crystals, and is famously associated with the unique mineral suite at Franklin, New Jersey.
Is this bustamite?
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 bustamite with a known reference. Bustamite sits at Mohs 5.5-6.5 — softer than the next harder reference, harder than the previous one.
- 2Check the streakDrag the specimen across an unglazed porcelain plate. Bustamite leaves a white streak.
- 3Read the lusterHold the specimen under a strong light. Bustamite typically shows a vitreous to pearly luster.
- 4Match the color rangeCompare against the expected color range: pink, reddish-pink, brownish-pink, gray.
- 5Look at form & habitCrystal system: triclinic. Typical habit: fibrous, massive, or granular aggregates.
Often confused with
Bustamite vs. its common look-alikes — and how to tell them apart in the field.
How to tell apart: Luster reads vitreous to pearly on Bustamite and vitreous on Rhodonite.
How to tell apart: Luster reads vitreous to pearly on Bustamite and vitreous on Wollastonite.
How to tell apart: Luster reads vitreous to pearly on Bustamite and vitreous to silky on Pectolite.
Often found alongside bustamite
Minerals reported to co-occur with bustamite. Spotting these in float or country rock is a strong cue you are in the right ground.
All properties
- Chemical formula
- (Ca,Mn)₃Si₃O₉
- Mohs hardness
- 5.5-6.5
- Density
- 3.3-3.4 g/cm³
- Streak
- White
- Luster
- Vitreous to Pearly
- Transparency
- Translucent
- Crystal system
- Triclinic
- Crystal habit
- Fibrous, Massive, Or Granular Aggregates
- Cleavage
- Perfect in Two Directions
- Rarity
- Uncommon
- Uses
- Collector, Lapidary
- Host rock
- Metamorphosed Manganese-rich Ore Deposits
- Typical price
- $10-100 per specimen
Where rockhounds find bustamite
Classic worldwide localities
- Franklin, New Jersey, USA
- Broken Hill, New South Wales, Australia
- Langban, Sweden
- Cap Garonne, France
Field-hunting tip
Look in metamorphosed manganese-rich ore deposits country — that is the host setting where bustamite typically forms. If you start seeing rhodonite, calcite, willemite in float, you are in the right ground. Field specimens usually show a fibrous, massive, or granular aggregates habit, so train your eye for that shape before scanning the outcrop.
Common questions
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Find bustamite on the map
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