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. Streak: white.
- 3Read the lusterHold the specimen under a strong light. Luster: vitreous.
- 4Match the color rangeCompare against the expected color range: pink, brown red, light pink.
- 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.
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
- 3.32-3.43 g/cm³
- Colors
- Streak
- White
- Luster
- Vitreous
- Transparency
- Transparent to translucent
- Crystal system
- Triclinic
- Crystal habit
- Fibrous, massive, or granular aggregates
- Cleavage
- Perfect on {100}, good on {110} and {110}, poor on {010}
- Fluorescence
- Pink red under LW UV
- Rarity
- Uncommon
- Uses
- Collector, Lapidary
- Host rock
- In manganese ores formed by metamorphism of manganese-bearing sediments with attendant metasomatism; typically associated with skarns
Where rockhounds find bustamite
Classic worldwide localities
- Franklin, Sussex Co., New Jersey, USA
- Långban and in the Harstigen mine, near Persberg, Värmland, Sweden
- Treburland mine, Altarnun, Cornwall, and in the Railroad quarry, Meldon, near Okehampton, Devon, England
- Camas Malag, Isle of Skye, Scotland
- Campiglia, Tuscany, and Schio, Vicenza, Italy
- N'Chwaning mine, near Kuruman, Cape Province, South Africa
Field-hunting tip
Where it forms: In manganese ores formed by metamorphism of manganese-bearing sediments with attendant metasomatism; typically associated with skarns. If you start seeing rhodonite, tephroite, calcite in float, you are in the right ground. Typical habit: fibrous, massive, or granular aggregates. Train your eye for that shape before scanning the outcrop.
Common questions
How do you identify bustamite?+
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Find bustamite on the map
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