Kimzeyite

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Formula: Ca₃Zr₂(SiAl₂)O₁₂
Nesosilicate (insular SiO₄ groups), schorlomite group, garnet supergroup, zirconium-bearing mineral
Crystal System: Isometric
Specific gravity: 4.0 measured, 4.03 calculated
Hardness: 7
Streak: Light brown
Colour: Dark Brown
Common impurities: Nb,Mg
Environments

Igneous environments
Carbonatites

Localities

At Stromboli Island, Lipari, Eolie Islands, Metropolitan City of Messina, Sicily, Italy, a study was carried out on lava flow and scoria samples collected from the last effusive activity (November 1975) of the island. The analysed samples are shoshonitic basalts. Minerals were separated from the lava sample with heavy liquids. The light fraction contains zoned plagioclase and some grains of saccharoidal blue quartz. The heavy fraction contains dark green pyroxene, olivine, dark green spinel, monticellite, and some brown garnets that proved to be kimzeyite (AM 65.188-191).

At the type locality, the Kimzey Calcite Quarry, Magnet Cove, Hot Spring County, Arkansas, USA, kimzeyite occurs in a light coloured phase of carbonatite, which is associated with ijolite in the quarry. Within the dominant white coarsely crystallised calcite are scattered irregular zones enriched in white to pale greenish finely prismatic apatite, massive light brown monticellite, and smaller but conspicuous black magnetite and perovskite, and in minor amounts some yellow vesuvianite, green mica and pyrite. The kimzeyite in this rock forms small dark brown crystals, usually under 1 mm across; some crystals contain considerable visible inclusions, mainly of apatite, calcite and monticellite, and many were found to contain microscopic clear crystals of anhydrite (AM 46.533-548).

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