Kapustinite is a rare silicate mineral belonging to the lomonosovite group, typically found in agpaitic alkaline igneous rocks. Collectors usually identify it by its yellowish-orange color and distinct platy or tabular habit in pegmatitic environments within the Kola Peninsula.
Is this kapustinite?
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 kapustinite with a known reference. Kapustinite 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: pale lilac.
- 3Read the lusterHold the specimen under a strong light. Luster: vitreous.
- 4Match the color rangeCompare against the expected color range: dark cherry red.
- 5Look at form & habitCrystal system: monoclinic. Typical habit: equant grains.
Often confused with
Kapustinite vs. its common look-alikes, and how to tell them apart in the field.
How to tell apart: Kapustinite is noticeably harder (Mohs 6 vs. 3-4); streak differs, so Kapustinite leaves pale lilac, Lomonosovite leaves light rose-cinnamon.
How to tell apart: Kapustinite is noticeably harder (Mohs 6 vs. 2-3); streak differs, so Kapustinite leaves pale lilac, Murmanite leaves white.
Often found alongside kapustinite
Minerals reported to co-occur with kapustinite. Spotting these in float or country rock is a strong cue you are in the right ground.
All properties
- Chemical formula
- Na₆ZrSi₆O₁₆(OH)₂
- Mohs hardness
- 6
- Density
- 2.78 g/cm³
- Colors
- Dark cherry red
- Streak
- Pale lilac
- Luster
- Vitreous
- Transparency
- Transparent to translucent
- Crystal system
- Monoclinic
- Crystal habit
- Equant grains
- Cleavage
- None
- Rarity
- Rare
- Uses
- Collector, Scientific research
- Host rock
- In hyperagpaitic pegmatite in an alkaline massif
Where rockhounds find kapustinite
Classic worldwide localities
- Palitra pegmatite, Kedykverpakhk Mountain, Lovozero alkaline massif, Kola Peninsula, Russia
Field-hunting tip
Where it forms: In hyperagpaitic pegmatite in an alkaline massif. If you start seeing microcline, aegirine, kazakovite in float, you are in the right ground. Typical habit: equant grains. Train your eye for that shape before scanning the outcrop.
Common questions
How do you identify kapustinite?+
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Find kapustinite on the map
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