Koashvite is a rare member of the eudialyte group found primarily in the agpaitic alkaline rocks of the Kola Peninsula. It typically occurs as reddish, tabular crystals embedded within pegmatitic zones of nepheline syenites. Collectors look for its characteristic trigonal symmetry and association with other rare-earth-bearing silicate minerals.
Is this koashvite?
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 koashvite with a known reference. Koashvite sits at Mohs 6, 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: vitreous.
- 4Match the color rangeCompare against the expected color range: brownish yellow, light yellow.
- 5Look at form & habitCrystal system: orthorhombic. Typical habit: tabular crystals, massive, granular.
Often confused with
Koashvite vs. its common look-alikes, and how to tell them apart in the field.
Often found alongside koashvite
Minerals reported to co-occur with koashvite. Spotting these in float or country rock is a strong cue you are in the right ground.
All properties
- Chemical formula
- Na₆CaTiSi₆O₁₈
- Mohs hardness
- 6
- Density
- 2.98-3.02 g/cm³
- Streak
- White
- Luster
- Vitreous
- Transparency
- Transparent
- Crystal system
- Orthorhombic
- Crystal habit
- Tabular crystals, massive, granular
- Cleavage
- None
- Rarity
- Rare
- Uses
- Collector, Scientific research
- Host rock
- As veinlets replacing lomonosovite in an ultra-agpaitic pegmatite in an alkalic massif
Where rockhounds find koashvite
Classic worldwide localities
- Mt. Koashva, Khibiny massif, Kola Peninsula, Russia
Field-hunting tip
Where it forms: As veinlets replacing lomonosovite in an ultra-agpaitic pegmatite in an alkalic massif. If you start seeing lomonosovite, pectolite, villiaumite in float, you are in the right ground. Typical habit: tabular crystals, massive, granular. Train your eye for that shape before scanning the outcrop.
Common questions
How do you identify koashvite?+
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What rocks look like koashvite?+
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Find koashvite on the map
RockHoundR shows mapped rockhounding spots, access rules, and lets you log every find.
