Monticellite is an uncommon calcium-magnesium silicate belonging to the olivine group. It typically occurs as small, pale prismatic crystals or granular aggregates in contact-metamorphosed limestone and is most often identified by its association with skarn minerals.
Is this monticellite?
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 monticellite with a known reference. Monticellite sits at Mohs 5 — softer than the next harder reference, harder than the previous one.
- 2Check the streakDrag the specimen across an unglazed porcelain plate. Monticellite leaves a white streak.
- 3Read the lusterHold the specimen under a strong light. Monticellite typically shows a vitreous luster.
- 4Match the color rangeCompare against the expected color range: colorless, white, gray, yellowish, brown.
- 5Look at form & habitCrystal system: orthorhombic. Typical habit: prismatic crystals, granular, massive.
Often confused with
Monticellite vs. its common look-alikes — and how to tell them apart in the field.
Often found alongside monticellite
Minerals reported to co-occur with monticellite. Spotting these in float or country rock is a strong cue you are in the right ground.
All properties
- Chemical formula
- CaMgSiO₄
- Mohs hardness
- 5
- Density
- 3.0-3.2 g/cm³
- Streak
- White
- Luster
- Vitreous
- Transparency
- Translucent
- Crystal system
- Orthorhombic
- Crystal habit
- Prismatic Crystals, Granular, Massive
- Cleavage
- Distinct On {010}
- Rarity
- Uncommon
- Uses
- Collector, Scientific Research
- Host rock
- Contact-metamorphosed Limestone or Dolomitic Marbles
- Typical price
- $15-100 per specimen
Where rockhounds find monticellite
1 mapped spotsClassic worldwide localities
- Mount Somma, Italy
- Magnet Cove, Arkansas, USA
- Kola Peninsula, Russia
- Crestmore, California, USA
Field-hunting tip
Look in contact-metamorphosed limestone or dolomitic marbles country — that is the host setting where monticellite typically forms. If you start seeing calcite, diopside, vesuvianite in float, you are in the right ground. Field specimens usually show a prismatic crystals, granular, massive habit, so train your eye for that shape before scanning the outcrop. In the U.S., the densest reported localities are in Arkansas — start trip planning there.
Common questions
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Find monticellite on the map
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