Pseudomarkeyite is a rare pseudomorph where calcium carbonate (calcite) has replaced the unstable mineral ikaite, which typically forms in cold marine sediments. Collectors prize these for their unique, often elongated or 'fleur-de-lis' crystal shapes that retain the structural history of the original ikaite phase. They are typically found in glacial-marine sediments and require careful handling due to the fragile nature of these pseudomorphs.
Is this pseudomarkeyite?
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 pseudomarkeyite with a known reference. Pseudomarkeyite sits at Mohs 3 — softer than the next harder reference, harder than the previous one.
- 2Check the streakDrag the specimen across an unglazed porcelain plate. Pseudomarkeyite leaves a white streak.
- 3Read the lusterHold the specimen under a strong light. Pseudomarkeyite typically shows a vitreous luster.
- 4Match the color rangeCompare against the expected color range: white, colorless, gray.
- 5Look at form & habitCrystal system: trigonal. Typical habit: pseudomorphs after ikaite.
Often confused with
Pseudomarkeyite vs. its common look-alikes — and how to tell them apart in the field.
Often found alongside pseudomarkeyite
Minerals reported to co-occur with pseudomarkeyite. Spotting these in float or country rock is a strong cue you are in the right ground.
All properties
- Chemical formula
- CaCO₃
- Mohs hardness
- 3
- Density
- 2.71 g/cm³
- Streak
- White
- Luster
- Vitreous
- Transparency
- Transparent
- Crystal system
- Trigonal
- Crystal habit
- Pseudomorphs After Ikaite
- Cleavage
- Perfect Rhombohedral
- Rarity
- Rare
- Uses
- Collector
- Host rock
- Sedimentary Marine Deposits
- Typical price
- $20-150 per specimen
Where rockhounds find pseudomarkeyite
Classic worldwide localities
- Greenland
- Canada
- Norway
Field-hunting tip
Look in sedimentary marine deposits country — that is the host setting where pseudomarkeyite typically forms. If you start seeing calcite, aragonite in float, you are in the right ground. Field specimens usually show a pseudomorphs after ikaite habit, so train your eye for that shape before scanning the outcrop.
Common questions
How do you identify pseudomarkeyite?+
Where is pseudomarkeyite found?+
How much is pseudomarkeyite worth?+
What rocks look like pseudomarkeyite?+
What minerals are found with pseudomarkeyite?+
What kind of rock does pseudomarkeyite form in?+
What is pseudomarkeyite used for?+
Find pseudomarkeyite on the map
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