The macro photography (size 3 x 4 cm) of Maw-Sit-Sit shows the finely matted structure of this jadeite-containing rock.
Foto: K. Sieber, www.makrogalerie.de
Maw-sit-site is a rock that consists of six main components that can vary significantly in quantity. The appearance of individual specimens can vary noticeably. This name is derived from a local name of its provenance near the town of Tawmaw in Burma (Myanmar) [Gübelin, 1978].
The rock consists of a groundmass of light-colored aggregates (mainly albite, but also zeolites and chlorite) in composition with numerous dark minerals, especially minerals of the jadeite-cosmochlor solid solution series of intense green color. These jadeite minerals can form single crystals or a blocky mosaic. In between, there are always black nests of fine felted cosmochlore (NaCrSi206), a chromium analogue of jadeite (NaAlSi206).
Due to the replacement of Al by Cr, maw-sit-sit contains wide sequences of a solid solution between cosmochlore and jadeite. In the centre of the cosmochlore nests metallically shiny chromite can be found in form of small residual grains. In addition, coarser crystals of grey to green colored amphibole or chrome-amphibole were formed. In the sixties and seventies of the last century this rock was also called "Jadealbit". However, since maw-sit-sit has been increasingly offered, hardly any albite can be found. As a consequence this appellation is considered obsolete.
References:
Börner, K. & Hill, D. (2012): Große Enzyklopädie der Steine; 15. Aufl.; Abraxas Verlag; Hasede, ISBN 978-3-934219-17-5.
Gübelin, E. (1964): Maw-sit-sit, a new decorative gemstone from Burma.- Gems & Gemmology; Vol. 11; Nr. 8; 227-238
Gübelin, E. (1978): Maw-sit-sit.- Lapis, Vol. 3, Nr. 10; 25-28
Henn, U. (2008): Bestimmungstabellen.- Deutsche Gemmologische Gesellschaft (DGemG); Eigenverlag
Schumann, W. (1997): Der neue BLV Steine- und Mineralienführer.- Blv Buchverlag; ISBN-10: 3405153026
Ou Yang, M.C. & Phil, M. (1993): Microscopic studies of Burmese jadeite-jade.- J. Gemmol. 23, 5, 278 - 284.
Webster, R. & Read, P.G. (2000): Gems, Their Sources, Descriptions and Identification.- Butterworth-Heinemann; 273-274; ISBN-10: 0750616741
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