Indianite

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Indianite
Inderite-91982.jpg
Water-clear, greasy inderite from the "US Borax" open pit mine near Boron , Kern County , California, USA (field of view 20 mm)
General and classification
other names

Lesserit (after Frondel)

chemical formula Mg [B 3 O 3 (OH) 5 ] • 5H 2 O
Mineral class
(and possibly department) 		Borates (formerly carbonates, nitrates and borates)
System no. to Strunz
and to Dana 		6.CA.15 ( 8th edition : V / H.06)
03/26/01/03
Crystallographic Data
Crystal system monoclinic
Crystal class ; symbol monoclinic prismatic; 2 / m
Room group (no.) P 2 1 / a (No. 14)
Lattice parameters a  = 12.04  Å ; b  = 13.11 Å; c  = 6.82 Å
β  = 104.5 °
Formula units Z  = 4
Frequent crystal faces {110}, {120}, {001}
Physical Properties
Mohs hardness 3
Density (g / cm 3 ) measured: 1.80; calculated: 1.794
Cleavage perfect after {010}, good after {1 1 0}
Break ; Tenacity shell-like to uneven
colour colorless, white, pink
Line color White
transparency transparent to translucent
shine Glass to pearlescent on cleavage surfaces, greasy gloss, matt
Crystal optics
Refractive indices n α  = 1.488
n β  = 1.491
n γ  = 1.505
Birefringence δ = 0.017
Optical character biaxial positive
Axis angle 2V = 37 ° (measured); 52 ° (calculated)

Inderite is a rarely occurring mineral from the mineral class of " borates " (formerly carbonates, nitrates and borates , see classification ). It crystallizes in the monoclinic crystal system with the composition Mg [B 3 O 3 (OH) 5 ] · 5H 2 O, so it is chemically a water-containing magnesium borate.

Inderite often develops long prismatic crystals with an almost square cross-section. But it also occurs in the form of fibrous to needle-like, kidney-bulbous or massive mineral aggregates . In its pure form, the mineral is colorless and transparent with a glass-like to fat-like sheen on the surfaces. However, due to multiple refraction due to lattice construction defects or polycrystalline formation, it can also appear white and, due to foreign admixtures, take on a pink color, the transparency decreasing accordingly.

With a Mohs hardness of 3, which corresponds to that of the reference mineral calcite , inderite is one of the medium-hard minerals that can be scratched with a copper coin.

Special properties

Matt white tarnished inderite from the "US Borax" open pit mine
(length of the comparative scale 1 inch (= 2.54 cm) with a notch at one centimeter)

If Inderite is left unprotected in the air, it will lose its crystal water over time and the crystal surfaces will turn matt white. However, the process can be reversed by immersing the mineral in water for a few minutes.

Etymology and history

Was first discovered in the Inderit boron - deposit on Indersee ( Inder lake , Indian salt dome ) in the area Atyrau in Kazakhstan and described in 1937 by AM Boldyreva, of the mineral after its type locality named. EN Egorova carried out the analyzes to determine the chemical composition.

In 1956, Clifford Frondel , Vincent Morgan and FLT Waugh described a new borate mineral from the open pit mine near Boron ( Kern County ) in the US state of California and named it lesserite . Waldemar Theodore Schaller and Mary E. Mrose found, however, on closer analysis in 1960 that lesserite is identical to inderite.

classification

In the 8th edition of the mineral systematics according to Strunz , which is now outdated, but still in use , Inderite still belonged to the common mineral class of " Carbonates , Nitrates and Borates" and there to the department of "Group Borates", where together with Meyerhofferit it formed the "Inderit-Meyerhofferit- Group "with the system no. V / H.06 and the other members Inderborit , Inyoit , Kurnakovit and Solongoit .

In contrast , the 9th edition of Strunz's mineral systematics, which has been in effect since 2001 and is used by the International Mineralogical Association (IMA), assigns inderite to the now independent class of "borates" and there in the department of "triborates". This is also further subdivided by the structural design of the borate complexes, so that the mineral according to its construction in the subdivision "Island Triborate (Neso-Triborate)" is to find where it is the only member of the unnamed group 6.CA.15 forms .

The systematics of minerals according to Dana , which is mainly used in the English-speaking area , assigns the Inderite, like the outdated Strunz system, to the common class of “carbonates, nitrates and borates” and there to the department and subdivision of the same name “26.03. Hydroxyl or halogen borates containing water ”. Here you can find him together with Inyoit and Inderborit in the unnamed group 26.03.01 .

Modifications and varieties

The compound Mg [B 3 O 3 (OH) 5 ] · 5H 2 O is dimorphic and occurs naturally as a triclinic crystallizing kurnakovite in addition to the monoclinic crystallizing modification inderite .

Education and Locations

Almost unweathered, double-ended inderite crystal from Boron, Kern County , California, USA (size: 8.9 × 2.1 × 2.3 cm)

Inderite forms in sedimentary form in lacustric boron deposits. As accompanying minerals may include Hydroboracite (Indersee, Kazakhstan), Kurnakovit , (Sarıkaya, Turkey) borax , Ulexit , orpiment , realgar (Boron, California, USA) occur.

As a rare mineral formation, Inderite could only be detected at a few sites, whereby so far (as of 2013) around 15 sites are known. Its type locality Indersee is the only known site in Kazakhstan to date.

Other previously known sites include the "Tincalayu Mine" at the Salar del Hombre Muerto salt lake in Argentina, the salt lakes in Da Qaidam (Qinghai) and Gê'gyai (Tibet) in China, the "Brosso Mine" in the Italian municipality of Lessolo ( Piedmontese Léssoj ), the boron deposit “Titovskoe” in the Tas-Khayakhtakh mountain range in the East Siberian Republic of Sakha (Yakutia) in Russia, the boron deposits at Kırka and Sarıkaya (Yozgat) in the Turkish region of Central Anatolia and the mining field “Hard Scramble "near Ryan ( Inyo County ) in the Black Mountains and at several locations of the boron or borax deposit in the vicinity of Boron ( Kern County ) in the US state of California .

The deposits in Boron are also known for their extraordinary inderite finds with well-formed crystals up to 10 centimeters long. However, inderite crystals up to 30 centimeters long are said to have been found.


Crystal structure

Inderite crystallizes monoclinically in the space group P 2 1 / a (space group no. 14) with the lattice parameters a  = 12.04  Å ; b  = 13.11 Å; c  = 6.82 Å and β = 104.5 ° and 4 formula units per unit cell .

use

Besides borax, inderite is mainly mined as boron ore for the chemical industry.

Occasionally, however, it is also offered in various gemstone cuts for collector's purposes . In fibrous form and using the cabochon -Schliffs Inderit can also especially when Tigereye known cat's eye effect show.

See also

literature

Web links

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

Individual evidence

  1. ↑ a b Mindat - Lesserite
  2. ↑ a b c d e 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.  342 .
  3. ↑ Webmineral - Inderite
  4. ↑ a b c d e Inderite , In: John W. Anthony, Richard A. Bideaux, Kenneth W. Bladh, Monte C. Nichols (Eds.): Handbook of Mineralogy, Mineralogical Society of America , 2001 ( PDF 66.2 kB )
  5. ↑ a b c Petr Korbel, Milan Novák: Mineral Encyclopedia . Nebel Verlag GmbH, Eggolsheim 2002, ISBN 3-89555-076-0 , p. 131 ( Dörfler Natur ).
  6. ↑ a b c Mindat - Inderite
  7. ^ Note from US mineralogist Rock Currier at mindat.org
  8. ↑ Mineralienatlas - type locality Inder See (accessed on June 26, 2014)
  9. ↑ E. Wm. Heinrich: A second discovery of Inderite , In: American Mineralogist , Volume 31 (1946) ( PDF 290 kB )
  10. ^ Carl Hintze , Karl F. Chudoba : Handbuch der Mineralogie. Supplementary volume 3: New minerals and new mineral names (with supplements, corrections and additions) , Walter de Gruyter, Leipzig 1968, ISBN 3-11-082179-6 , p. 494 in the Google book search
  11. ↑ Mindat - Number of localities for Inderit
  12. ↑ Find location list for Inderite at the Mineralienatlas and at Mindat
  13. ^ Walter Schumann: Precious stones and gemstones. All species and varieties in the world. 1600 unique pieces . 13th revised and expanded edition. BLV Verlags-GmbH., Munich et al. 2002, ISBN 3-405-16332-3 , p. 238 .