Ankerite is a common member of the dolomite group that often displays characteristic brownish or yellowish staining due to iron oxidation. It typically forms sharp rhombohedral crystals and is frequently found in hydrothermal vein deposits alongside other carbonates and sulfide minerals.
Is this ankerite?
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 ankerite with a known reference. Ankerite 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. Ankerite leaves a white streak.
- 3Read the lusterHold the specimen under a strong light. Ankerite typically shows a vitreous luster.
- 4Match the color rangeCompare against the expected color range: white, yellow, brown, gray.
- 5Look at form & habitCrystal system: trigonal. Typical habit: rhombohedral crystals.
Often confused with
Ankerite vs. its common look-alikes — and how to tell them apart in the field.
Often found alongside ankerite
Minerals reported to co-occur with ankerite. Spotting these in float or country rock is a strong cue you are in the right ground.
All properties
- Chemical formula
- Ca(Fe,Mg,Mn)(CO₃)₂
- Mohs hardness
- 3.5-4
- Density
- 2.9-3.1 g/cm³
- Streak
- White
- Luster
- Vitreous
- Transparency
- Translucent
- Crystal system
- Trigonal
- Crystal habit
- Rhombohedral Crystals
- Cleavage
- Perfect Rhombohedral
- Rarity
- Common
- Uses
- Collector, Geological Specimen
- Host rock
- Hydrothermal Veins and Sedimentary Environments
- Typical price
- $5-50 thumbnail, $20-150 cabinet
Where rockhounds find ankerite
5 mapped spotsClassic worldwide localities
- Austria
- Czech Republic
- USA
- Italy
- Canada
Field-hunting tip
Look in hydrothermal veins and sedimentary environments country — that is the host setting where ankerite typically forms. If you start seeing siderite, dolomite, calcite in float, you are in the right ground. Field specimens usually show a rhombohedral crystals habit, so train your eye for that shape before scanning the outcrop. In the U.S., the densest reported localities are in Colorado, Massachusetts, North Carolina — start trip planning there.
Common questions
How do you identify ankerite?+
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Find ankerite on the map
RockHoundR shows mapped rockhounding spots, access rules, and lets you log every find.
