Penkvilksite is a rare titanium-bearing silicate mineral found in the alkaline massifs of the Kola Peninsula. It typically occurs as small, platy, or tabular crystals nestled within pegmatite pockets of igneous complexes.
Is this penkvilksite?
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 penkvilksite with a known reference. Penkvilksite sits at Mohs 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: pearly or silky on fresh fracture; dull on the surface.
- 4Match the color rangeCompare against the expected color range: white, colorless.
- 5Look at form & habitCrystal system: monoclinic. Typical habit: porcelainous.
Often confused with
Penkvilksite vs. its common look-alikes, and how to tell them apart in the field.
How to tell apart: Luster reads pearly or silky on fresh fracture; dull on the surface on Penkvilksite and vitreous on Steacyite.
How to tell apart: Luster reads pearly or silky on fresh fracture; dull on the surface on Penkvilksite and vitreous to dull on Eudialyte.
Often found alongside penkvilksite
Minerals reported to co-occur with penkvilksite. Spotting these in float or country rock is a strong cue you are in the right ground.
All properties
- Chemical formula
- Na₄Ti₂Si₈O₂₂·4H₂O
- Mohs hardness
- 5
- Density
- 2.58 g/cm³
- Streak
- White
- Luster
- Pearly or silky on fresh fracture; dull on the surface
- Transparency
- Transparent to translucent
- Crystal system
- Monoclinic
- Crystal habit
- Porcelainous
- Cleavage
- One perfect, probably basal
- Rarity
- Rare
- Uses
- Collector
- Host rock
- In the central natrolite zone of a pegmatite in a differentiated alkalic massif (Lovozero massif, Russia)
Where rockhounds find penkvilksite
Classic worldwide localities
- Jubilee pegmatite, on Mt. Karnasurt, Lovozero massif, Kola Peninsula, Russia
- Mont Saint-Hilaire, Quebec, Canada
Field-hunting tip
Where it forms: In the central natrolite zone of a pegmatite in a differentiated alkalic massif (Lovozero massif, Russia). If you start seeing aegirine, natrolite, mountainite in float, you are in the right ground. Typical habit: porcelainous. Train your eye for that shape before scanning the outcrop.
Common questions
How do you identify penkvilksite?+
Where is penkvilksite found?+
What rocks look like penkvilksite?+
What minerals are found with penkvilksite?+
What kind of rock does penkvilksite form in?+
What is penkvilksite used for?+
Find penkvilksite on the map
RockHoundR shows mapped rockhounding spots, access rules, and lets you log every find.
