s
Russian Gemstones Encyclopedia

Vladimir Bukanov. Russian Gemstones Encyclopedia

A B C D E F G H I J K L M N O P Q R S T U V W X Y Z

XENOTIME


XENOTIME (Xenotim—Xénotime— сенотим) (Beudant, F.S. 1832). The earliest usage of the name may be Berzelius (1824), whereby the Gk. “xenos” a stranger, refers to the mineral’s occurrence in small and rare crystals that were long overlooked. Beudant (1832), however, who gives the first complete description, says the name is from “kenos” – stranger, plus “time”, honor, because its contained yttrium had been mistakenly thought to be a new element. Xenotime was also called yttrium spar.

Composition & Properties. Phosphate – Y[PO4], tetragonal system. Hardness 4-5.5. Density 4.4-5.1. Glass luster. Fragile. Cleavage in one direction. Sometimes it is radioactive. Translucent to non-transparent. Color: yellow-brownish to dark brownish, sometimes with greenish tint. Xenotime is a rare mineral usually found in the form of bipyramidal or columnar crystals. It looks like cassiterite, clinohumite and zircon.

Deposits. It is found in pegmatites; it is stable to weathering; it is accumulated on placers. In Russia, xenotime, as well as monazite, was discovered in pegmatites of North Karelia, at the Elovyi Navolok locality, near Louchskoye Lake. In Kyrgyzstan, it was discovered at the Ak-Tyuz deposit, to the east from Bishkek. In Tadzhikistan, in the West Pamirs Mts., they found its transparent light brown crystals up to 5x1 cm. in the Pijon River, near the Yazgulem settlement. In Switzerland, transparent crystals of yellowish-green xenotime in alpine veins Poncione Della Fibbia deposit, Ticino canton, reached 1 cm. long. In South Norway, they were found at the deposits Odderstol and Hitterø. In Mozambique, at the Ribaue deposit, in the Alto Ligonha Region, they discovered xenotime crystals up to 6 cm. They were also found in South Africa, at the Wessels deposit, North Cape Prov. In 1995, in Brazil, in the Bahia State, at the Ibiajara (form. Ibitiara) deposit they began to extract gem-quality crystals of xenotime up to 3 cm. in size; and in Minas Gerais, at the Sabinópolis deposit – up to 2 cm. In Japan, xenotime crystals were found at the Takayama deposit, Gifu Pref.; and at Yamanoo, Ibaraki (Ibaragi), near Ösaka.; and at the Ishikawa deposit, Fukushima Pref., it was found in basalts in the form of radial-rayed clusters with crystals of zircon. Such basalts are used sometimes as an ornamental stone under the trade names kiku-ishy, kiku-kwa-seki or chrysanthemium stone.

Faceted xenotime is of collection interest only.
Search