Keldyshite is a rare sodium zirconium silicate primarily found in alkaline igneous environments like the Kola Peninsula. It is typically identified by its tabular or platy crystal habit and is often associated with other rare zirconium-bearing minerals in pegmatite pockets. Because of its rarity and resemblance to other alkaline silicates, it is highly prized by advanced mineral collectors.
Is this keldyshite?
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 keldyshite with a known reference. Keldyshite sits at Mohs 3.8-4.3, 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 greasy.
- 4Match the color rangeCompare against the expected color range: white.
- 5Look at form & habitCrystal system: triclinic. Typical habit: platy crystals, tabular aggregates.
Often confused with
Keldyshite vs. its common look-alikes, and how to tell them apart in the field.
Often found alongside keldyshite
Minerals reported to co-occur with keldyshite. Spotting these in float or country rock is a strong cue you are in the right ground.
All properties
- Chemical formula
- Na₂ZrSi₂O₇
- Mohs hardness
- 3.8-4.3
- Density
- 3.22-3.30 g/cm³
- Colors
- Streak
- White
- Luster
- Vitreous to greasy
- Transparency
- Translucent, transparent in thin fragments
- Crystal system
- Triclinic
- Crystal habit
- Platy crystals, tabular aggregates
- Cleavage
- Two poor, intersecting ~90°
- Rarity
- Rare
- Uses
- Collector
- Host rock
- A primary mineral in foyaites composed of partly albitized microcline, nepheline, sodalite, aegirine, and alkali amphibole, in a differentiated alkalic massif (Lovozero massif, Russia)
Where rockhounds find keldyshite
Classic worldwide localities
- Vicinity of the Tavaiok and Angoundasiok Rivers and on Mt. Alluaiv, Lovozero massif, and at Tachtarvumchorr, Khibiny massif, Kola Peninsula, Russia
- Lågendalen, near Larvik, Norway
Field-hunting tip
Where it forms: A primary mineral in foyaites composed of partly albitized microcline, nepheline, sodalite, aegirine, and alkali amphibole, in a differentiated alkalic massif (Lovozero massif, Russia). If you start seeing eudialyte, lorenzenite in float, you are in the right ground. Typical habit: platy crystals, tabular aggregates. Train your eye for that shape before scanning the outcrop.
Common questions
How do you identify keldyshite?+
Where is keldyshite found?+
What rocks look like keldyshite?+
What minerals are found with keldyshite?+
What kind of rock does keldyshite form in?+
What is keldyshite used for?+
Find keldyshite on the map
RockHoundR shows mapped rockhounding spots, access rules, and lets you log every find.
