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Sphalerite Gemstone

The most  amazing  thing  about  collecting coloured gemstones is that Mother Nature never fails to shock you. Until February 2009, all I  knew about Sphalerite was that the Smithsonian Museum of Natural History and the Liverpool World Museum had samples of this mineral; I  had never contemplated setting the mineral in jewellery and had therefore not written about it before.

Then over dinner one day, a very good friend of mine told me he had recently seen a specimen that was bright orange and that it had an amazing  amount  of  dispersion.  The  next  day  I  spent several hours on the internet researching the gem type and was amazed at what I found. My friend’s  observation of a strong amount of fire was very  accurate indeed: the gem has a dispersion that is  over three times that of a Diamond (technically speaking it has a B-G interval of  0.156)!

Sphalerite  consists  mainly  of  Zinc  and  Iron.  Normally  the  Iron  content  dominates  and  the  mineral looks similar to the dull pieces seen in  the  museums.  Most  Sphalerite  is  opaque  and  black and is sometimes referred to as Marmatite  (was this the origin of our Marmite spread or  was it a French stew?). Isn’t the gem world so  exciting, when the graphite in your pencil has the  exact same chemical composition as a Diamond  (see  allotropic)  and  dull  old  Marmatite  is  the  same  mineral  as  the  most  incredibly  dazzling  and  monumentally  rare  Sphalerite!  To  my  knowledge only a handful of yellow, orange and  red specimens have been found so far.

Only  two  mines  have  ever  been  reported  to  discover gem quality pieces; the Chivera mine,  in Sonora Mexico and the Las Manforas Mine in  the Picos de Europa Montains (the first national  park  in  Spain)  located  on  the  North  Coast  of  Spain near Santander. Its name is derived from  the Greek word for ‘treacherous rock’, as non-gem quality specimens can easily be confused  with other minerals. The gem is also known as  Blende which is the German word for ‘blind’  (most likely so for the same reason as the Greek  meaning).

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