Dolomite is a common carbonate mineral that forms distinct, often saddle-shaped rhombohedral crystals. It is easily distinguished from calcite because it will only effervesce in dilute hydrochloric acid when powdered.
Is this dolomite?
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 dolomite with a known reference. Dolomite sits at Mohs 3.5-4 — softer than the next harder reference, harder than the previous one.
- 2Check the streakDrag the specimen across an unglazed porcelain plate. Dolomite leaves a white streak.
- 3Read the lusterHold the specimen under a strong light. Dolomite typically shows a vitreous luster.
- 4Match the color rangeCompare against the expected color range: white, gray, pink, colorless, brown, yellow.
- 5Look at form & habitCrystal system: trigonal. Typical habit: rhombohedral crystals with curved faces, massive, granular.
Often confused with
Dolomite vs. its common look-alikes — and how to tell them apart in the field.
Often found alongside dolomite
Minerals reported to co-occur with dolomite. Spotting these in float or country rock is a strong cue you are in the right ground.
All properties
- Chemical formula
- CaMg(CO₃)₂
- Mohs hardness
- 3.5-4
- Density
- 2.84 g/cm³
- Streak
- White
- Luster
- Vitreous
- Transparency
- Translucent
- Crystal system
- Trigonal
- Crystal habit
- Rhombohedral Crystals with Curved Faces, Massive, Granular
- Cleavage
- Perfect in 3 Directions
- Fluorescence
- Often White, Yellow, Or Orange Under SW UV
- Rarity
- Common
- Uses
- Industrial, Collector, Construction
- Host rock
- Sedimentary Carbonate Rocks, Hydrothermal Veins
- Typical price
- $5-30 thumbnail, $20-150 cabinet
Where rockhounds find dolomite
57 mapped spotsClassic worldwide localities
- Eugui, Spain
- St. Gotthard, Switzerland
- Ontario, Canada
- Missouri, USA
U.S. states with dolomite
Each link opens a state-specific list of mapped rockhounding spots that produce dolomite.
Field-hunting tip
Look in sedimentary carbonate rocks, hydrothermal veins country — that is the host setting where dolomite typically forms. If you start seeing calcite, fluorite, barite in float, you are in the right ground. Field specimens usually show a rhombohedral crystals with curved faces, massive, granular habit, so train your eye for that shape before scanning the outcrop. In the U.S., the densest reported localities are in Missouri, Tennessee, West Virginia — start trip planning there.
Common questions
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Find dolomite on the map
RockHoundR shows mapped rockhounding spots, access rules, and lets you log every find.
