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, 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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