Calzirtite is a rare zirconium-bearing oxide mineral typically found in carbonatite complexes. It usually occurs as dark, submetallic octahedral crystals or irregular grains, often embedded within carbonate-rich rocks.
Is this calzirtite?
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 calzirtite with a known reference. Calzirtite sits at Mohs 6 — softer than the next harder reference, harder than the previous one.
- 2Check the streakDrag the specimen across an unglazed porcelain plate. Calzirtite leaves a yellowish-brown streak.
- 3Read the lusterHold the specimen under a strong light. Calzirtite typically shows a submetallic luster.
- 4Match the color rangeCompare against the expected color range: dark brown, reddish-brown, black.
- 5Look at form & habitCrystal system: tetragonal. Typical habit: octahedral crystals, granular masses.
Often confused with
Calzirtite vs. its common look-alikes — and how to tell them apart in the field.
How to tell apart: Zircon is the harder of the two (Mohs 7.5 vs. 6); streak differs — Calzirtite leaves yellowish-brown, Zircon leaves white; luster reads submetallic on Calzirtite and adamantine on Zircon.
How to tell apart: Streak differs — Calzirtite leaves yellowish-brown, Baddeleyite leaves white.
How to tell apart: Streak differs — Calzirtite leaves yellowish-brown, Perovskite leaves white; luster reads submetallic on Calzirtite and adamantine on Perovskite.
Often found alongside calzirtite
Minerals reported to co-occur with calzirtite. Spotting these in float or country rock is a strong cue you are in the right ground.
All properties
- Chemical formula
- CaZr₃TiO₉
- Mohs hardness
- 6
- Density
- 4.92 g/cm³
- Streak
- Yellowish-brown
- Luster
- Submetallic
- Transparency
- Opaque
- Crystal system
- Tetragonal
- Crystal habit
- Octahedral Crystals, Granular Masses
- Cleavage
- None
- Rarity
- Rare
- Uses
- Collector
- Host rock
- Carbonatites, Alkaline Igneous Rocks
- Typical price
- $50-300 per specimen
Where rockhounds find calzirtite
Classic worldwide localities
- Kola Peninsula, Russia
- Jacupiranga Mine, Brazil
- Aldan Shield, Russia
Field-hunting tip
Look in carbonatites, alkaline igneous rocks country — that is the host setting where calzirtite typically forms. If you start seeing baddeleyite, perovskite, magnetite in float, you are in the right ground. Field specimens usually show a octahedral crystals, granular masses habit, so train your eye for that shape before scanning the outcrop.
Common questions
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Find calzirtite on the map
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