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, so Calzirtite leaves yellowish-brown, Zircon leaves white; luster reads submetallic on Calzirtite and adamantine on Zircon.
How to tell apart: Streak differs, so Calzirtite leaves yellowish-brown, Baddeleyite leaves white.
How to tell apart: Streak differs, so 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, 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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