Shark wide

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Shark wide
Haiweeite-Gypsum-171826.jpg
Haiweeit aggregates in plaster from Brazil, size: 6.5 × 5.6 × 1.9 cm
General and classification
other names
  • Ranquilite
  • ICSD 85085
chemical formula
  • Ca (UO 2 ) 2 (Si 5 O 12 ) (OH) 2 · 6H 2 O
  • Ca [(UO 2 ) 2 | (OH 2 ) | Si 5 O 12 ] • 4.5H 2 O
Mineral class
(and possibly department) 		Silicates and germanates - layered silicates (phyllosilicates)
System no. to Strunz
and to Dana 		9.AK.25 ( 8th edition : VIII / A'.15)
53.03.02.02
Crystallographic Data
Crystal system orthorhombic
Crystal class ; symbol orthorhombic-dipyramidal; 2 / m  2 / m  2 / m
Space group Pbcn (No. 60)Template: room group / 60
Lattice parameters a  = 18.30  Å ; b  = 14.23 Å; c  = 17.92 Å
Formula units Z  = 8
Physical Properties
Mohs hardness 3.5
Density (g / cm 3 ) measured: 3.35; calculated: [4.93]
Cleavage good after {100}
colour light yellow to yellow
Line color White
transparency translucent
shine Pearlescent
radioactivity very strong with 85.16 k Bq / g
Crystal optics
Refractive indices n α  = 1.560 to 1.571
n β  = 1.575 to 1.580
n γ  = 1.578 to 1.582
Birefringence δ = δ = 0.018
Optical character biaxial negative
Axis angle 2V = 15 ° (measured); 46 ° to 50 ° (calculated)
Other properties
Chemical behavior soluble in acids

Haiweeit is a rarely occurring minerals from the mineral class of "silicates and germanates" with the chemical composition Ca (UO 2 ) 2 (Si 5 O 12 ) (OH) 2 · 6H 2 O and chemical point of a hydrous calcium - uranyl - silicate with additional hydroxide ions .

Haiweeit crystallizes in the orthorhombic crystal system and develops short, needle-like or flake-like crystals , but also radial mineral aggregates of light yellow to greenish yellow in color. The surfaces of the translucent crystals show a pearlescent sheen on the surfaces.

Etymology and history

Haiweeit was named after its location, the Haiwee Reservoir , Coso Mountains , Inyo County , California in the USA , where it was discovered in 1959 and described by Thomas Chester McBurney and Joseph Murdoch.

classification

In the now outdated 8th edition of the mineral classification according to Strunz , the Haiweeit belonged to the mineral class of "silicates and Germanates" and there to the department of "Neso-Subsilikate", where together with Weeksit it belonged to the "Weeksit group" belonging to the uranyl silicate family “With the system no. VIII / A'.15 formed.

In the last revised and updated Lapis mineral directory by Stefan Weiß in 2018 , which, out of consideration for private collectors and institutional collections, is still based on this classic system of Karl Hugo Strunz , the mineral was given the system and mineral number. VIII / H.37-20 . In the “Lapis system” this also corresponds to the class “Silicates and Germanates”, but there the department “Layered Silicates”, where Haiweeit, together with Weeksit, Coutinhoit and Metahaiweeit, forms an independent but unnamed group.

The 9th edition of Strunz's mineral systematics, which has been valid since 2001 and updated by the International Mineralogical Association (IMA) until 2009, again classifies the Haiweeit under the category of "island silicates (nesosilicates)". This is further subdivided according to the possible presence of further anions, the structure or the molar ratio of uranium:  silicon . Haiweeit can be found in the department of "Uranyl island and polysilicates with the molar ratio U: Si = 2: 1", where together with Metahaiweeit the "Haiweeit group" with the system no. 9.AK.25 forms.

The systematics of minerals according to Dana , which is mainly used in the English-speaking world , assigns the Haiweeit to the class of "silicates and germanates" and there in the department of "island silicates: SiO 4 groups and other anions of complex cations". Here he is together with Coutinhoit, Metahaiweeit and Weeksit in the "Weeksit group" with the system no. 53.03.02 within the subsection “ Island silicates with SiO 4 groups and other anions as well as complex cations with (UO 2 ) ”.

Crystal structure

Haiweeit crystallizes orthorhombically in the space group Pbcn (space group no. 60) with the lattice parameters a  = 18.30  Å ; b  = 14.23 Å ​​and c  = 17.92 Å and 8 formula units per unit cell . Template: room group / 60

properties

The mineral is very radioactive due to its uranium content of over 52.8% . Taking into account the proportions of the radioactive elements in the idealized empirical formula and the Folgezerfälle of the natural decay chains a specific activity of about 85,16 k for the mineral Bq stated / g (compared to natural potassium 0.0312 kBq / g). The quoted value can vary significantly depending on the mineral content and the composition of the levels; selective enrichment or depletion of the radioactive decay products is also possible and changes the activity. The mineral fluoresces slightly greenish under UV light .

Education and Locations

Haiweeit is found as a secondary mineral in the oxidation zone of uranium deposits and superficially broken pegmatites , along tourmaline-open fractures in granites and in cavities of compacted sediments . As Begleitminerale occur among other Autunit , meta-autunite , Uranophan , Uranophan-beta , Phosphuranylit , Torbernit , meta Torbernit , Chernikovit and Opal on (Peru District, São Paulo, Brazil).

There are only a small number of known localities of the shark, apart from the type locality Coso Mountains: Mammoth Mine in Texas , USA, Margaritas No.1 Mine, Nopal Mine, and Animas Mine in Chihuahua , Mexico , Ningyo-Toge Mine (Ningyo -Tohge Mine) on Honshu in Japan , Minas Gerais , Bahia and São Paulo in Brazil , Portezuelo Hill, Ranquil District in Argentina , Radhausberg near Salzburg in Austria , Saskatchewan in Canada , Rössing Mine in Namibia and the Los Azules Mine in Chile and others Locations.

Precautions

Due to the radioactivity of the mineral, mineral samples from the Haiweeit should only be kept in dust- and radiation-proof containers, but above all never in living rooms, bedrooms or workrooms. Likewise, because of the high toxicity and radioactivity of uranyl compounds, absorption into the body ( incorporation , ingestion ) should be prevented in any case and, for safety, direct body contact should be avoided and respiratory protection mask and gloves should be worn when handling the mineral .

See also

literature

  • William GR de Camargo, Darcy P. Svisero: Haiweeite, a new occurrence in Bazil . In: American Mineralogist . tape 54 , 1969, p. 966–969 (English, minsocam.org [PDF; 237 kB ; accessed on September 14, 2019]).
  • Peter C. Burns: A new uranyl silicate sheet in the structure of Haiweeite and comparison to other uranyl silicates . In: The Canadian Mineralogist . tape 39 , 2001, p. 1153–1160 (English, rruff.info [PDF; 603 kB ; accessed on September 14, 2019]).

Web links

Commons : Haiweeite  - Collection of images, videos and audio files

Individual evidence

  1. ↑ a b Stefan Weiß: The large Lapis mineral directory. All minerals from A - Z and their properties. Status 03/2018 . 7th, completely revised and supplemented edition. Weise, Munich 2018, ISBN 978-3-921656-83-9 .
  2. ↑ a b c David Barthelmy: Haiweeite Mineral Data. In: webmineral.com. Retrieved September 14, 2019 .
  3. ↑ a b c d Jakub Plášil, Karla Fejfarová, Jiří Čejka, Michal Dušek, Radek Škoda, Jiří Sejkora: Revision of the crystal structure and chemical formula of haiweeite, Ca (UO 2 ) 2 (Si 5 O 12 ) (OH) 2 6H 2 O . In: American Mineralogist . tape 98 , 2013, p. 718–723 (English, abstract available at minsocam.org [PDF; 234 kB ; accessed on September 14, 2019]).
  4. ↑ Malcolm Back, William D. Birch, Michel Blondieau and others: The New IMA List of Minerals - A Work in Progress - Updated: September 2019. (PDF 2672 kB) In: cnmnc.main.jp. IMA / CNMNC, Marco Pasero, September 2019, accessed September 14, 2019 .
  5. ^ Hugo Strunz , Ernest H. Nickel : Strunz Mineralogical Tables. Chemical-structural Mineral Classification System . 9th edition. E. Schweizerbart'sche Verlagbuchhandlung (Nägele and Obermiller), Stuttgart 2001, ISBN 3-510-65188-X , p.  566 (English).
  6. ↑ a b c d shark width . In: John W. Anthony, Richard A. Bideaux, Kenneth W. Bladh, Monte C. Nichols (Eds.): Handbook of Mineralogy, Mineralogical Society of America . 2001 ( handbookofmineralogy.org [PDF; 314  kB ; accessed on September 14, 2019]).
  7. ↑ a b c d e f Haiweeite. In: mindat.org. Hudson Institute of Mineralogy, accessed September 14, 2019 .
  8. ↑ Ernest H. Nickel, Monte C. Nichols: IMA / CNMNC List of Minerals 2009. (PDF 1703 kB) In: cnmnc.main.jp. IMA / CNMNC, January 2009, accessed September 14, 2019 .
  9. ↑ Find location list for Haiweeit at the Mineralienatlas and at Mindat