Calciomurmanite is a rare phyllosilicate mineral typically found in agpaitic nepheline syenite pegmatites. It most commonly appears as platy, micaceous crystals that exhibit a distinct pearly luster on cleavage surfaces, often found in association with sodium-rich minerals.
Is this calciomurmanite?
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 calciomurmanite with a known reference. Calciomurmanite sits at Mohs 2.5-3, softer than the next harder reference, harder than the previous one.
- 2Check the streakDrag the specimen across an unglazed porcelain plate. Streak: white.
- 3Read the lusterHold the specimen under a strong light. Luster: pearly on cleavage; greasy on fracture surfaces.
- 4Match the color rangeCompare against the expected color range: pale brown, purple.
- 5Look at form & habitCrystal system: triclinic. Typical habit: platy crystals, foliated aggregates.
Often confused with
Calciomurmanite vs. its common look-alikes, and how to tell them apart in the field.
How to tell apart: Luster reads pearly on cleavage; greasy on fracture surfaces on Calciomurmanite and vitreous on cleavages, greasy on fractures on Murmanite.
How to tell apart: Streak differs, so Calciomurmanite leaves white, Lomonosovite leaves light rose-cinnamon; luster reads pearly on cleavage; greasy on fracture surfaces on Calciomurmanite and vitreous to adamantine on cleavages, greasy on fractures on Lomonosovite.
Often found alongside calciomurmanite
Minerals reported to co-occur with calciomurmanite. Spotting these in float or country rock is a strong cue you are in the right ground.
All properties
- Chemical formula
- (Ca□)Ti₂(Na□)Ti₂(Si₂O₇)₂O₂(OH)₂(H₂O)₄
- Mohs hardness
- 2.5-3
- Density
- 2.70 g/cm³
- Colors
- Streak
- White
- Luster
- Pearly on cleavage; greasy on fracture surfaces
- Transparency
- Translucent
- Crystal system
- Triclinic
- Crystal habit
- Platy crystals, foliated aggregates
- Cleavage
- Perfect on {001}, distinct on two other directions nearly ⊥ to one another and (001)
- Rarity
- Rare
- Uses
- Collector
- Host rock
- nepheline syenite pegmatites
Where rockhounds find calciomurmanite
Classic worldwide localities
- Mt. Flora, Lovozero complex and Mt. Eveslogchorr and the Koashva open pit, Vostochnyi apatite mine, Khibiny complex, Kola Peninsula, Russia
Field-hunting tip
Where it forms: nepheline syenite pegmatites. If you start seeing microcline, aegirine, lorenzenite in float, you are in the right ground. Typical habit: platy crystals, foliated aggregates. Train your eye for that shape before scanning the outcrop.
Common questions
How do you identify calciomurmanite?+
Where is calciomurmanite found?+
What rocks look like calciomurmanite?+
What minerals are found with calciomurmanite?+
What kind of rock does calciomurmanite form in?+
What is calciomurmanite used for?+
Find calciomurmanite on the map
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