Yugawaralith
| Yugawaralith | |
|---|---|
 |
|
| General and classification | |
| chemical formula | Ca [Al 2 Si 6 O 16 ] • 4H 2 O |
|
Mineral class (and possibly department) |
Silicates and Germanates - framework silicates |
|
System no. to Strunz and to Dana |
9.GB.15 ( 8th edition : VIII / J.25) 77.01.07.02 |
| Crystallographic Data | |
| Crystal system | monoclinic |
| Crystal class ; symbol | monoclinic; m |
| Room group (no.) | Pc (No. 7) |
| Lattice parameters |
a = 6.73 Å ; b = 14.00 Å; c = 10.07 Å β = 111.1 ° |
| Formula units | Z = 2 |
| Physical Properties | |
| Mohs hardness | 4.5 to 5 |
| Density (g / cm 3 ) | measured: 2.20 to 2.23; calculated: 2.26 |
| Cleavage | imperfect after {10 1 }, clearly after {40 1 }, {100} |
| Break ; Tenacity | brittle and fragile |
| colour | colorless, white |
| Line color | White |
| transparency | transparent to translucent |
| shine | Glass luster, pearlescent luster; iridescent after {010} |
| Crystal optics | |
| Refractive indices |
n α = 1.495 n β = 1.497 n γ = 1.504 |
| Birefringence | δ = 0.009 |
| Axis angle | 2V = 78 ° (measured); 58 ° (calculated) |
| Other properties | |
| Special features | piezoelectric, pyroelectric |
Yugawaralith is a rarely occurring mineral from the mineral class of "silicates and germanates". It crystallizes in the monoclinic crystal system with the chemical composition Ca [Al 2 Si 6 O 16 ] · 4H 2 O and thus chemically seen a hydrous calcium - aluminum - silicate . Structurally, Yugawaralith belongs to the family of zeolites within the framework of the tectosilicates .
Yugawaralith mostly develops tabular crystals of up to eight centimeters in length, which are often arranged in groups of almost parallel crystal tables. In its pure form, Yugawaralith is colorless and transparent with a glass-like sheen on the surfaces. However, due to multiple light refraction due to lattice construction defects or polycrystalline formation, it can also appear white, with the transparency decreasing accordingly.
Special properties
Yugawaralith is piezoelectric and pyroelectric , so it reacts to periodically changing pressure and temperature changes by building up an electrical voltage .
Etymology and history
Yugawaralith was first discovered in 1930 in the Andesitic rocks flowed through by thermal springs in the vicinity of Yugawara (Kanagawa Prefecture) on the Japanese island of Honshū and described in 1952 by Kin-Ichi Sakurai (1912-1993) and A. Hayashi, who named the mineral after his Type locality and the ancient Greek word λίθος lithos for "stone". Put together, the name means "stone from Yugawara".
The type material of the mineral is kept in the National Museum Tokyo in Japan, the Mines ParisTech ( École des mines de Paris ) in France and in the National Museum of Natural History in Washington, DC in the USA (Catalog No. 106164, 106931).
classification
Already in the outdated, but partly still in use 8th edition of the mineral systematics according to Strunz , the yugawaralite belonged to the mineral class of "silicates and germanates" and there to the division of "tectosilicates (tectosilicates), with zeolites", where together with amicite , garronite , Gismondin , Gobbinsit , Harmotom , Merlinoit , Montesommait , Phillipsit-Ca , Phillipsit-K and Phillipsit-Na within the zeolite group the subgroup of the "leaf zeolites III" with the system no. VIII / J.25 formed.
The 9th edition of Strunz's mineral systematics , which has been in effect since 2001 and is used by the International Mineralogical Association (IMA), also assigns the Yugawaralith to the division of “tectosilicates with zeolitic H 2 O; Family of zeolites ”. However, this is further subdivided according to the framework structure, so that the mineral can be found according to its structure in the sub-section "Chains of simply connected rings of four", where it is the only member of the unnamed group 9.GB.15 .
The systematics of minerals according to Dana , which is mainly used in the English-speaking world , assigns the Yugawaralith to the class of "silicates and germanates" and there in the department of "framework silicates: zeolite group". Here it is together with Brewsterit-Sr , Brewsterit-Ba , Goosecreekit and Roggianit in the group " Brewsterite and allied species " with the system no. 77.01.07 to be found within the subdivision of "Real Zeolites".
Education and Locations
Yugawaralith forms hydrothermally and is therefore mostly found as a crack and vein filling and as a cavity filling in geodes in active, geothermal areas. Accompanying minerals are other minerals of the zeolite group and generally silicates such as gyrolite , okenite and prehnite , but also quartz and / or calcite .
As a rare mineral formation, Yugawaralith could only be proven at a few sites, whereby so far (as of 2014) around 40 sites are known. In addition to its type locality Yugawara, the mineral occurred in Japan in the "Seikoshi" gold and silver mine near Toi-cho ( Shizuoka prefecture ), at Okiura / Kuroishi (Aomori prefecture) and in the geothermal field around the Onikobe volcano ( Miyagi prefecture ) on Honshū and at Nukabira / Obihiro (sub-prefecture Tokachi) on Hokkaidō.
Well-known localities for well-formed Yugawaralith crystal specimens are among the quarries around Malad and Mumbai in the Mumbai City district in the Indian state of Maharashtra and the Yellow Lake near Olalla in the Canadian province of British Columbia .
Other locations include Argentina, Iceland, Italy, New Zealand, Réunion, Ukraine, Hungary and the United States of America.
Crystal structure
Yugawaralith crystallizes monoclinically in the space group Pc (space group no. 7) with the lattice parameters a = 6.73 Å ; b = 14.00 Å; c = 10.07 Å and β = 111.1 ° and two formula units per unit cell .
The crystal structure of Yugawaralith contains building blocks of SiO 4 - and AlO 4 - tetrahedra , which are connected to each other to four- and five-membered rings parallel (100) and via further four-membered rings approximately perpendicular to (100). Together, the ring structure forms a framework with channels made of eight-membered rings parallel to the a- and c-axes. The eight-fold coordinated sodium ions are integrated at the nodes and the crystal water they contain is stored in the channels.
use
Yugawaralith has so far not had any particular significance as a raw material or for commercial use as a gemstone . Occasionally, however, it is offered to collectors in different shapes .
See also
literature
- Kin-Ichi Sakurai, A. Hayashi: Yugawaralite, a new zeolite. In: Science Reports of the Yokohama National University. Volume 1, 1952, pp. 69-77. ( PDF 428.1 kB )
- Kazuo Harada, Kin-Ichi Sakurai: Chemical composition and optical properties of yugawaralite from the type locality. In: The American Mineralogist. Volume 54, 1969, pp. 306-309. ( PDF 248.5 kB )
- Friedrich Klockmann : Klockmann's textbook of mineralogy . Ed .: Paul Ramdohr , Hugo Strunz . 16th edition. Enke , Stuttgart 1978, ISBN 3-432-82986-8 , pp. 796 (first edition: 1891).
Web links
- Mineral Atlas: Yugawaralith (Wiki)
- Database-of-Raman-spectroscopy - Yugawaralite
- American-Mineralogist-Crystal-Structure-Database - Yugawaralite
Individual evidence
- ↑ a b c d e f 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. 703 .
- ↑ Webmineral - Yugawaralite
- ↑ a b c d e Yugawaralite. In: John W. Anthony, Richard A. Bideaux, Kenneth W. Bladh, Monte C. Nichols (Eds.): Handbook of Mineralogy, Mineralogical Society of America. 2001. ( PDF 80.3 kB )
- ↑ a b c Mindat - Yugawaralite
- ↑ Mineralogical Records: Kinichi Sakurai (1912-1993)
- ↑ Mindat - Number of localities for Yugawaralite
- ↑ Find location list for Yugawaralith in the Mineralienatlas and in [Mindat]
- ^ Walter Schumann: Precious stones and gemstones. All species and varieties in the world. 1600 unique pieces . 13th, revised and expanded edition. BLV Verlag, Munich et al. 2002, ISBN 3-405-16332-3 , p. 232 .
- ↑ realgems.org - Yugawaralith (with picture of a cut stone)