Huttonite

from Wikipedia, the free encyclopedia
Huttonite
General and classification
chemical formula Th [4 + 5] [SiO 4 ]
Mineral class
(and possibly department) 		Silicates and Germanates
System no. to Strunz
and to Dana 		9.AD.35 ( 8th edition : VIII / A.11)
05.51.03.01
Crystallographic Data
Crystal system monoclinic
Crystal class ; symbol monoclinic prismatic 2 / m
Space group P 2 1 / n
Lattice parameters a  = 6.80  Å ; b  = 6.96 Å; c  = 6.54 Å
β  = 104.9 °
Formula units Z  = 4
Physical Properties
Mohs hardness 4.5 to 5
Density (g / cm 3 ) measured: 7.1; calculated: 7.18
Cleavage indistinct after {001}
Break ; Tenacity shell-like
colour light yellow to almost colorless
Line color White
transparency transparent to translucent
shine Diamond luster
radioactivity very strong
Crystal optics
Refractive indices n α  = 1.898
n β  = 1.900
n γ  = 1.922
Birefringence δ = 0.024
Optical character biaxial positive
Other properties
Special features fluorescent

The mineral huttonite is a rare island silicate with the chemical composition Th [4 + 5] [SiO 4 ]. It crystallizes in the monoclinic crystal system and develops only microscopic, light yellow to almost colorless crystals of about 0.2 mm in size or grainy, brown-black aggregates . The Huttonite is usually metamictic, i.e. its crystal structure is destroyed due to its own ionizing radiation .

Etymology and history

Huttonite was first discovered in 1950 in the surf sands of "Gillespie's Beach" of Salt Water Creek in the South Westland of the West Coast of New Zealand and described in 1951 by Adolf Pabst (1899–1990), who named the mineral after the New Zealand-American mineralogist from Stanford University , Colin Osborne Hutton (1910-1971), named.

classification

In the now outdated, but still in use 8th edition of the mineral classification according to Strunz , the huttonite belonged to the mineral class of "silicates and germanates" and there to the general division of " island silicates (nesosilicates)", where it has its own together with tombarthite (Y) Group formed.

The 9th edition of Strunz's mineral systematics , which has been in effect since 2001 and is used by the IMA, also assigns the Huttonite to the class of "Silicates and Germanates" and there in the section of "Island silicates (Nesosilicates)". In the meantime, however, this section has been subdivided more precisely according to the presence of further anions and the coordination of the cations , so that the mineral is classified in the subdivision of “island silicates without further anions; Cations in octahedral [6] and usually larger coordination “can be found, where it, also together with tombarthite- (Y), forms the unnamed group 9.AD.35 .

The systematics of minerals according to Dana also assigns the Huttonite to the class of "silicates" and there to the department of "island silicates". Here it is the eponymous mineral of the "Huttonite group" with the other member tombarthite (Y) and the system no. 05.51.03 within the sub-section " Island silicates: SiO 4 groups only with cations in> [6] coordination "

Crystal structure

Unit cell of Huttonite
green = thorium, gray = silicon, red = oxygen

Huttonite crystallizes isotypically with monazite in the monoclinic crystal system in the space group P 2 1 / n with the lattice parameters a  = 6.80  Å ; b  = 6.96 Å; c  = 6.54 Å and β = 104.9 ° and 4 formula units per unit cell .

properties

The mineral is classified as very radioactive due to its thorium content of up to 71.59% and has a specific activity of around 32.072 k Bq / g (for comparison: natural potassium 31.2 Bq / g).

Under UV light with a short wavelength, some Huttonites show fluorescence from white to slightly pink .

Modifications and varieties

The compound Th [SiO 4 ] is dimorphic , that is, it occurs in nature as tetragonally crystallizing thorite in addition to the monoclinically crystallizing huttonite .

Education and Locations

So far nothing is known about the exact formation conditions, as the Huttonite could only be filtered out of different coastal sands.

Apart from its type locality "Gillespie's Beach", Huttonite could not be detected at any other site in New Zealand . The mineral has been found in more than 20 locations worldwide so far (as of 2010), for example in the “United Brothers Mine” near Sunnyside (Omeo) in East Gippsland Shire and at Lake Boga in the Australian state of Victoria ; near Glees , Kruft and Mendig in the Eifel in Germany; at Forssa in Finland; at Thiruvananthapuram (Trivandrum) in India; at Monte Mort ( Saint-Rhémy-en-Bosses , Aosta Valley), Monte Somma (Campania) and in the “Finero Ultramafit Complex” in the province of Verbano-Cusio-Ossola in Italy; in the rare earth - deposit at Aktyuz in Kyrgyzstan ; in the Bogatyn area in the Polish Lower Silesian Voivodeship ; in the Aldan highlands , near Lowosero (Kola, Murmansk) and on Lake Ishkul near Chelyabinsk in Russia; at Krokom ( Jämtland ) and Råneå ( Norrbotten ) in Sweden; in the Pilansberg complex near Rustenburg in South Africa; near Šluknov and Třebíč in the Czech Republic and in the “Holiday Uranium Mine” in the Fitting district in Mineral County (Nevada) and in Fern in Florence County (Wisconsin) in the USA.

See also

literature

Web links

Commons : Huttonite  - collection of images, videos and audio files

Individual evidence

  1. ↑ a b c Webmineral - Huttonite (English)
  2. ↑ a b c d Hugo Strunz , Ernest H. Nickel: Strunz Mineralogical Tables . 9th edition. E. Schweizerbart'sche Verlagbuchhandlung (Nägele and Obermiller), Stuttgart 2001, ISBN 3-510-65188-X , p. 543 .
  3. ↑ a b Handbook of Mineralogy - Huttonite (English, PDF 75.1 kB)
  4. ↑ a b Huttonite at mindat.org (engl.)
  5. ↑ Mineral Atlas: Huttonite
  6. ↑ Mindat - Localities for Huttonite