Fivegite is a rare beryllium-bearing silicate mineral discovered within the hyper-alkaline Ilimaussaq complex of Greenland. It is structurally related to tugtupite and is typically found as small, inconspicuous grains within rare-earth-rich pegmatitic rocks. Collectors prize it primarily for its mineralogical rarity rather than its aesthetic display qualities.
Is this fivegite?
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 fivegite with a known reference. Fivegite sits at Mohs 4, 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 to pearly.
- 4Match the color rangeCompare against the expected color range: colorless.
- 5Look at form & habitCrystal system: orthorhombic. Typical habit: massive to granular.
Often confused with
Fivegite vs. its common look-alikes, and how to tell them apart in the field.
Often found alongside fivegite
Minerals reported to co-occur with fivegite. Spotting these in float or country rock is a strong cue you are in the right ground.
All properties
- Chemical formula
- K₄Ca₂[AlSi₇O₁₇(O₀(OH)₂)][(H₂O)₀(OH)₂]Cl
- Mohs hardness
- 4
- Density
- 2.42 g/cm³
- Colors
- Streak
- White
- Luster
- Vitreous to pearly
- Transparency
- Transparent
- Crystal system
- Orthorhombic
- Crystal habit
- Massive to granular
- Cleavage
- Perfect on {100}, distinct on {010}
- Rarity
- Rare
- Uses
- Collector
- Host rock
- A late-stage hydrothermal phase in high-potassium peralkaline pegmatite in urtite near the contact with nepheline-apatite rock
Where rockhounds find fivegite
Classic worldwide localities
- Central mine (southern wall, 640 m level), Mt. Rasvumchorr, Khibiny massif, Kola Peninsula, Russia
Field-hunting tip
Where it forms: A late-stage hydrothermal phase in high-potassium peralkaline pegmatite in urtite near the contact with nepheline-apatite rock. If you start seeing delhayelite, hydrodelhayelite, pectolite in float, you are in the right ground. Typical habit: massive to granular. Train your eye for that shape before scanning the outcrop.
Common questions
How do you identify fivegite?+
Where is fivegite found?+
What rocks look like fivegite?+
What minerals are found with fivegite?+
What kind of rock does fivegite form in?+
What is fivegite used for?+
Find fivegite on the map
RockHoundR shows mapped rockhounding spots, access rules, and lets you log every find.
