Jasper (Quartz)

 

Composition Silicon dioxide SiO2 Crystal system trigonal (cryptocrystalline)
Hardness (Moh´s)
 61/2 - 7 Density 2,58- 2,91
Refractive index 1,54 aprox. Birefringence -
Pleocroisme
 - Fluorescence -
Fracture
 conchiode. I. Dispertion -
Cleavage
 none Streak variated
Absortion: not determinated.

 

  • The name comes from the greek iaspis = jasper = blemish stone. In olden days this name was used for a lot of stones. Actually the jasper is considered a cryptocrystalline quartz the wich one, for somebody is part of the chalcedony group and for other people is part of an independent group due a granular structure. it´s found in nodules or filling fisures.
  • Have variated colours, like its composition and physical property due that it contains strange materials. It can be in one colour: red, yellow etc. but frequently it´s found like a multicolour in band, stain, colours like flames etc.Tranlucent to opaque.
  • Localities in península ibérica: a lot. It detach the jasper from Montjuïc, Barcelona, used since the prehistory, due the great colours variety.
  • Treatments: It´s not usual but can be dyed.
  • Uses: like an ornamental material, balls, cab for to be used in jewellery.


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© Montse Bagué and Josep M. Serrano.Text and photos. Reproduction not allowed without permission.