Kerolite

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Kerolite
Chryzopras Polsko.jpg
Chrysoprase, colored intensely green by adding cerolite
General and classification
other names
  • Kerolite
  • Cerolite
  • Hydrosilicit
  • Shell talc
chemical formula (Mg, Ni) 3 Si 4 O 10 (OH) 2 · H 2 O
Mineral class
(and possibly department) 		Silicates and Germanates
System no. according to Strunz formerly December 9th, 2005, as it has since been discredited
Similar minerals Willemseit (pimelite), talc , saponite (soap stone)
Crystallographic Data
Crystal system monoclinic
Crystal class ; symbol Please complete!
Physical Properties
Mohs hardness 2 to 2.5
Density (g / cm 3 ) 2.3 to 2.4
Cleavage Please complete!
Break ; Tenacity uneven to scalloped
colour white, yellowish green, gray green to bottle green
Line color greenish white
transparency transparent to translucent
shine Glass gloss to pronounced greasy gloss
Other properties
Chemical behavior decomposes in acids, can be melted with a soldering iron
Special features The characteristic intense green color persists only in darkness and in a damp environment

Kerolite is now considered by the majority as a nickel-containing variety of talc . Since 1979 it is no longer considered an independent mineral due to the doubt about its specific independence . In the literature it is also called mineral mixture of serpentine and saponite (soap stone) from the mineral class of the silicates described. Kerolites occur preferentially in dense, greasy to the touch, coarse, amorphous masses.

Etymology and history

The cerolite was described for the first time by Breithaupt in 1823 from a sample from the Frankenstein area in Silesia . Because of its characteristic soapy, sometimes smeary to waxy feel, Breithaupt called it a wax stone (Greek κηρός 'wax', λίθος 'stone').

Around the same time Otto Kuh described the mineral as hydrosilicate . This name is therefore often given as a synonym in the literature. Since cerolite mainly occurs as an adhesion, admixture or storage in other minerals, its specific independence is controversial today.

properties

Breithaupt's description of kerolite (1832)

Kerolite aggregates are subject to natural aging, combined with discoloration of the originally green mineral. It is due to the release of water in a warm environment and under the influence of sunlight. Aged, dehydrated kerolites are white-gray to waxy yellow and opaque. The aging process - and with it the discoloration - can be stopped in (mountain) damp surroundings and reversed to a certain extent.

With regard to the examination of the hygroscopic properties, August Breithaupt described the cerolite in 1823 as a substance that does not hang on the tongue in order to underline the special position of the mineral in the group of opal-like talc minerals he was investigating .

However, he defined the greasy, greasy to waxy feel as the salient diagnostic feature . In the soldering tube preliminary test, the cerolite-soda mixture showed a light red color when it was blown out in the oxidation flame, which Breithaupt attributed to traces of lithium in the sample.

Education and Locations

Kerolite forms during the decomposition or chemical weathering of magnesium and nickel containing ultrabasic rocks. In the best investigated Gläsendorf deposit , kerolite occurs together with pimelite (Ni saponite) and stevensite (Mn saponite) in a network of thin fissures in the transition area between highly altered and less decomposed ultrabasic rocks.

Kerolite was described by Breithaupt at various sites in Saxony : in the serpentinite from Zöblitz as platy aggregates, in Hartmannsdorf , in the almond stone from Oberhohndorf and from various basalts from Bohemia and Saxony ( Stolpen and Hauenstein). Important sites of kerolite are also in Poland in the district of Frankenstein (Frankenstein, Gläsendorf, exhausted), in England ( Cornwall , St. Keverne), in the Urals (Elov mine near Yekaterinburg , near Magnitogorsk , Svetly and Orsk near Orenburg ), in the US, including Hawai (Kauai), Maine (Thomaston, Union and Warren), Nevada (Nye County), North Carolina (Macon County, Madison County) and Massachusetts (Essex County). There are also deposits in New Caledonia ( Yaté ), Italy (near Balangero ), Sweden ( Dalarna ) and in Eastern Cameroon .

Use as a gem stone

The intense apple-green color of chrysoprase , a variety of chalcedony , is due to a finely distributed addition of cerolite. However, the high sensitivity of cerolite to heat and drying out limits its processing as a gemstone.

Chrysoprase, which is intensely green in color due to the presence of kerolite, was particularly popular in the past. The numerous wall coverings and table tops from Ząbkowice Śląskie (Frankenstein, Silesia) that Frederick the Great had made for Sanssouci Palace became famous . Numerous chrysoprase panels also adorn the walls of St. Wenceslas Chapel in St. Vitus Cathedral in Prague .

In some European crown insignia, including the crown of the Norwegian queen , chrysoprase containing kerolite is used.

See also

literature

  • A. Breithaupt: About Kerolite and Allophane . In: Seidel's year book of chemistry and physics . tape 25 , no. 3 , 1829, p. 306 .
  • GW Brindley, DL Bish, H.-M. Wan: The nature of kerolite, its relation to talc and stevensite . In: Mineralogical Magazine . tape 41 , 1977, pp. 443–452 ( minersoc.org [PDF; 679 kB ; accessed on November 23, 2017]).
  • E. Dubinska, BA Sakharov, P. Bylina, G. Kapron: Interstratified Kerolite-Stevensite from Szklary (Lower Silesia, Poland) . In: Scripta Fac. Sci. Nat. Univ. Masaryk Brun . No. 26 , 1998, pp. 23 .
  • HB v. Foullon: Over some nickel ore deposits . In: Yearbook of the royal and imperial Reichsanstalt . tape 43 , no. 2 . Vienna 1892, p. 223-310 .
  • Richard J. Léveillé, Fred John Longstaffe, William S. Fyfe: Kerolite in carbonate rich speleothems and microbial deposits from basaltic caves, Kauai, Hawaii . In: Clays and Clay Minerals . tape 50 , no. 4 , August 2002, p. 514-524 , doi : 10.1346 / 000986002320514235 .
  • B. Ullrich, K. Gensel, D. Kutschke: Combined thermoanalytical investigations on hydrothermal conversion products of the bronzite serpentinite from Kiefernberg (Hohenstein-Ernstthal, Saxony). Part 1. Kerolite . Jena 2002, p. 133-144 .

Web links

Individual evidence

  1. ↑ IMA / CNMNC List of Mineral Names 2009 (PDF; 1.9 MB)
  2. ↑ a b August Breithaupt: Complete characteristics of the mineral system . Arnoldische Buchhandlung, Dresden 1823, p. 145, 254 .
  3. ↑ Kerolit in Szklary (Silesia) ( Memento from April 11, 2008 in the Internet Archive ), accessed February 15, 2012.
  4. ^ NJ Elton, JJ Hooper, VAD Holyer: An occurrence of stevensite and kerolite in the Devonian Crousa Gabbro at Dean Quarry, The Lizard, Cornwall, England . In: Clay Minerals . tape 32 , 1997, pp. 241-252 , doi : 10.1180 / claymin.1997.032.2.06 .
  5. ^ R. Hermann: About the occurrence of kerolite in the Urals . In: Journ. f. practical chemistry . tape 95 , 1865, pp. 134-136 , doi : 10.1002 / prac.18650950111 .
  6. ↑ Vladimir Bouška, Vitalij J. Sobolevskij: Chalcedon a jeho varianty . In: Klenoty přírody . Lidové nakladatelství, Praha 1990, ISBN 80-7022-063-5 , p. 150-152 .
  7. ↑ Walter Schumann: Noble stones . BLV, Munich [u. a.] 2000, ISBN 3-405-15944-X , p. 90 .