Kosnarite Locality: Jenipapo district, Itinga , Jequitinhonha valley, Minas Gerais , Southeast Region, Brazil ( Locality at mindat.org ) Size: 8.2 x 5.7 x 4.2 cm. Kosnarite is Potassium, Zirconium Phosphate and was named after Richard Kosnar in 1994. The type locality for this material is Mt. Mica, Maine, and the crystals at that find barely approached 1 mm in diameter. A few years ago, Luiz Menezes made a discovery of what are the finest crystallized Kosnarite specimens in existence with crystals up to 4 mm (which is a quantum leap in size)!! This is a specimen from that find featuring sharp, lustrous, yellow color, pseudo-cubic (trigonal) crystals with brownish Lepidolite on white Albite matrix. If you look closely, you’ll see a small truncated face on each "cube" of Kosnarite on this specimen, which is actually a pinacoid or a "c" face as these crystals are trigonal and not isometric as they might appear. Ex. Richard Kosnar Collection. — Photo: Robert M. Lavinsky · CC BY-SA 3.0
Kosnarite
A potassium-zirconium phosphate named for Colorado pegmatite expert and mineral dealer Rich Kosnar.
Intro adapted from Wikipedia (CC BY-SA).
Kosnarite is an IMA-recognized mineral species in the phosphate class, with the chemical formula KZr₂(PO₄)₃.
It crystallizes in the hexagonal crystal system (space group R-3c).
Key properties: Mohs hardness 4.5; specific gravity 3.194; White streak; Vitreous luster; optically uniaxial.
IMA symbol Ksn, IMA status: approved, named in 1991.
A very rare mineral, formed by late hydrothermal alteration, probably of beryl and zircon, in complex granite pegmatites.
It is found associated with Eosphorite, fluorapatite, moraesite, siderite, zircon, quartz (Mt. Mica, Maine, USA); siderite, albite, quartz (Black Mountain quarry, Maine, USA).
The name refers to Richard A. Kosnar (1946–), American mineral dealer of Black Hawk, Colorado, USA, long interested in pegmatite minerals.