Grumantite is a rare sodium-silicate mineral found primarily in the hyperalkaline complexes of the Kola Peninsula. It typically forms delicate bladed or fibrous white to colorless crystals, often appearing as radiating sprays within nepheline syenite pegmatites.
Is this grumantite?
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 grumantite with a known reference. Grumantite sits at Mohs 4-5, 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, silky to dull in aggregates.
- 4Match the color rangeCompare against the expected color range: white, snow white.
- 5Look at form & habitCrystal system: orthorhombic. Typical habit: compact.
Often confused with
Grumantite vs. its common look-alikes, and how to tell them apart in the field.
Often found alongside grumantite
Minerals reported to co-occur with grumantite. Spotting these in float or country rock is a strong cue you are in the right ground.
All properties
- Chemical formula
- NaHSi₂O₅·H₂O
- Mohs hardness
- 4-5
- Density
- 2.21 g/cm³
- Colors
- Streak
- White
- Luster
- Vitreous, silky to dull in aggregates
- Transparency
- Transparent to slightly turbid in crystals
- Crystal system
- Orthorhombic
- Crystal habit
- Compact
- Cleavage
- Perfect on {110}; another unspecified cleavage was observed
- Fluorescence
- Weak bluish white under SW UV
- Rarity
- Rare
- Uses
- Collector
- Host rock
- In veins cutting alkalic feldspathoid-bearing pegmatites in a differentiated alkalic massif
Where rockhounds find grumantite
Classic worldwide localities
- Mt. Alluaiv, Lovozero massif, Kola Peninsula, Russia
Field-hunting tip
Where it forms: In veins cutting alkalic feldspathoid-bearing pegmatites in a differentiated alkalic massif. If you start seeing ussingite, makatite, kazakovite in float, you are in the right ground. Typical habit: compact. Train your eye for that shape before scanning the outcrop.
Common questions
How do you identify grumantite?+
Where is grumantite found?+
What rocks look like grumantite?+
What minerals are found with grumantite?+
What kind of rock does grumantite form in?+
What is grumantite used for?+
Find grumantite on the map
RockHoundR shows mapped rockhounding spots, access rules, and lets you log every find.
