Kimzeyite Identification Guide
Identify Kimzeyite, a rare zirconium-titanium garnet from Magnet Cove, by its dark brown color and carbonatite setting.
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What Kimzeyite Looks Like
Kimzeyite is a rare zirconium- and titanium-rich garnet. It is typically dark brown to brownish-black, with a vitreous-to-resinous luster and translucent-to-opaque diaphaneity. As a garnet it crystallizes in the isometric system, forming dodecahedra, trapezohedra, or anhedral grains. Its dark color and high density reflect substantial Zr, Ti, and Fe.
Quick visual cues
- Dark brown-black equant garnet crystals/grains
- Glassy to resinous luster
- No cleavage; conchoidal fracture
- Found in carbonatites and associated skarns
Step-by-Step Field ID Checklist
- Confirm garnet morphology: isometric crystals, no cleavage.
- Note color: dark brown-black, like other Ti/Zr garnets (schorlomite, kerimasite).
- Check the host: carbonatite/alkaline complexes and contact skarns are the classic environment.
- Test hardness: Mohs ~7, scratches glass.
- Heft: high density (~3.8-4.0) from Zr + Fe.
- Streak: pale brown/gray, non-metallic.
Key Diagnostic Tests
- Mohs hardness: ~7-7.5.
- Density: ~3.8-4.0 g/cm^3 (high).
- Cleavage/fracture: none/conchoidal.
- Streak: white to pale brown.
- Acid: no fizz (separates the garnet from carbonate matrix that does fizz).
- Definitive ID: electron microprobe/XRD—relative Zr/Ti separates it from schorlomite and kerimasite.
Common Look-Alikes and How to Tell Them Apart
- Schorlomite: Ti-dominant dark garnet; kimzeyite is the Zr-Ti-rich member—lab chemistry required.
- Kerimasite: the Zr-dominant relative; distinguished from kimzeyite by detailed site occupancy (lab).
- Melanite (Ti-andradite): black andradite without essential Zr.
- Magnetite/ilmenite: dark and dense but metallic, magnetic, with dark streaks; kimzeyite is non-metallic and non-magnetic.
Where It Is Found
The type locality is Magnet Cove, Arkansas, USA (named for the Kimzey family), within a carbonatite complex; similar Zr-garnets occur in alkaline-carbonatite intrusions worldwide. It is a collector and research mineral, not a gem.
Frequently asked questions
How do you identify Kimzeyite?
Look for dark brown-to-black isometric garnet crystals with no cleavage, a hardness near 7, high density (3.8-4.0), and a non-metallic streak, occurring in carbonatites and skarns; only chemical analysis confirms its zirconium-titanium content.
What is Kimzeyite and where was it discovered?
It is a rare zirconium-titanium silicate garnet first described from the Magnet Cove carbonatite complex in Arkansas, USA, where it is named after the Kimzey family.
Kimzeyite vs schorlomite—how do they differ?
Both are dark garnets, but kimzeyite is enriched in zirconium while schorlomite is titanium-dominant; they look alike and require microprobe or X-ray analysis to tell apart.
Is Kimzeyite magnetic?
No, it is non-magnetic with a pale non-metallic streak, which separates it from dark, magnetic, metallic minerals like magnetite and ilmenite.