Xenotime
| Xenotime | ||
|---|---|---|
Specific gravity 4.4–5.1 | | |
| Refractive index | 1.720–1.815 | |
| Birefringence | δ = 0.096 | |
| Pleochroism | Dichroic | |
| Other characteristics | Not radioactive or luminescent | |
| References | [2][3][4][5] | |
Xenotime is a
Etymology
The name xenotime is from the Greek words κενός vain and τιμή honor, akin to "vainglory". It was coined by French mineralogist François Sulpice Beudant as a rebuke of another scientist, Swedish chemist Jöns Jacob Berzelius, for the latter's premature claim to have found in the mineral a new chemical element (later understood to be previously discovered yttrium). The criticism was blunted, as over time "kenotime" was misread and misprinted "xenotime"[2][3][5] with the error suggesting the etymology ξένος + τιμή as "different honor". Xenotime was first described for an occurrence in Vest-Agder, Norway in 1824.[3]
Properties
Crystallising in the
Xenotime has two directions of perfect prismatic
Occurrence
Occurring as a minor accessory mineral, xenotime is found in pegmatites and other igneous rocks, as well as gneisses rich in mica and quartz. Associated minerals include biotite and other micas, chlorite group minerals, quartz, zircon, certain feldspars, analcime, anatase, brookite, rutile, siderite and apatite. Xenotime is also known to be diagenetic: It may form as minute grains or as extremely thin (less than 10 µ) coatings on detrital zircon grains in siliciclastic sedimentary rocks. The importance of these diagenetic xenotime deposits in the radiometric dating of sedimentary rocks is only beginning to be realised.[6]
Discovered in 1824, xenotime's type locality is Hidra (Hitterø), Flekkefjord, Vest-Agder, Norway. Other notable localities include: Arendal and Tvedestrand, Norway; Novo Horizonte, São Paulo, Novo Horizonte, Bahia and Minas Gerais, Brazil; Madagascar and California, Colorado, Georgia, North Carolina and New Hampshire, United States. A new discovery of gemmy, colour change (brownish to yellow) xenotime has been reported from Afghanistan and been found in Pakistan. North of Mount Funabuse in Gifu Prefecture, Japan, a notable basaltic rock is quarried at a hill called Maru-Yama: crystals of xenotime and zircon arranged in a radiating, flower-like pattern are visible in polished slices of the rock, which is known as chrysanthemum stone (translated from the Japanese 菊石 kiku-ishi). This stone is widely appreciated in Japan for its ornamental value.
Small tonnages of xenotime sand are recovered in association with Malaysian tin mining, etc. and are processed commercially. The lanthanide content is typical of "yttrium earth" minerals and runs about two-thirds yttrium, with the remainder being mostly the heavy lanthanides, where the even-numbered lanthanides (such as Gd, Dy, Er, or Yb) each being present at about the 5% level, and the odd-numbered lanthanides (such as Tb, Ho, Tm, Lu) each being present at about the 1% level. Dysprosium is usually the most abundant of the even-numbered heavies, and holmium is the most abundant of the odd-numbered heavies. The lightest lanthanides are generally better represented in monazite while the heaviest lanthanides are in xenotime.
See also
References
- S2CID 235729616.
- ^ ISBN 978-0199383-344.
- ^ a b c Mindat database.
- ^ Webmineral.
- ^ a b Handbook of Mineralogy.
- ^ "Geoconferences (WA) Inc". Archived from the original on December 14, 2006. Retrieved January 8, 2006. Daniela Vallini
Further reading
- Webster, R. (2000). Gems: Their sources, descriptions and identification (5th ed.), p. 182. Butterworth-Heinemann, Great Britain. ISBN
External links
Media related to Xenotime at Wikimedia Commons
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