Genthelvite is a rare zinc-beryllium sulfide member of the helvite group, often appearing as distinct, sharp tetrahedral crystals. It is most commonly found in highly evolved alkaline igneous complexes where it forms within cavities or veins alongside other rare minerals.
Is this genthelvite?
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 genthelvite with a known reference. Genthelvite sits at Mohs 6-6.5 — softer than the next harder reference, harder than the previous one.
- 2Check the streakDrag the specimen across an unglazed porcelain plate. Genthelvite leaves a white streak.
- 3Read the lusterHold the specimen under a strong light. Genthelvite typically shows a vitreous luster.
- 4Match the color rangeCompare against the expected color range: pink, red, yellow, white, colorless.
- 5Look at form & habitCrystal system: cubic. Typical habit: tetrahedral crystals, massive, granular.
Often confused with
Genthelvite vs. its common look-alikes — and how to tell them apart in the field.
Often found alongside genthelvite
Minerals reported to co-occur with genthelvite. Spotting these in float or country rock is a strong cue you are in the right ground.
All properties
- Chemical formula
- Zn₄Be₃(SiO₄)₃S
- Mohs hardness
- 6-6.5
- Density
- 3.6-3.7 g/cm³
- Streak
- White
- Luster
- Vitreous
- Transparency
- Translucent
- Crystal system
- Cubic
- Crystal habit
- Tetrahedral Crystals, Massive, Granular
- Cleavage
- Poor
- Fluorescence
- Weak to Moderate Green Under SW UV
- Rarity
- Rare
- Uses
- Collector
- Host rock
- Alkaline Igneous Rocks, Pegmatites, Syenites
- Typical price
- $50-500 thumbnail
Where rockhounds find genthelvite
Classic worldwide localities
- Mont Saint-Hilaire, Canada
- Kola Peninsula, Russia
- Sweden
- USA
Field-hunting tip
Look in alkaline igneous rocks, pegmatites, syenites country — that is the host setting where genthelvite typically forms. If you start seeing microcline, aegirine, nepheline in float, you are in the right ground. Field specimens usually show a tetrahedral crystals, massive, granular habit, so train your eye for that shape before scanning the outcrop.
Common questions
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Find genthelvite on the map
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