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THE  CORUNDUMINIUM

 
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BURMA

 
 

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       Burma is generally regarded for the finest rubies, against which all others are compared.  However, the country has numerous corundum localities that produce everything from ugly specimens only a geologist could love to the finest of gemstones.  It is arguably host to the most significant and diverse corundum distribution in the World.    
       Unfortunately, gem ruby crystals are very hard to obtain.  Politics (a.k.a. the embargo) and the fact that gem crystals are often sold directly to cutters contribute to this.  Now (early 2012), it appears the first problem may be thawing.   
     
     
 

PAINITE WITH RUBIES

 
     
      The mineral painite was considered one of the Worlds rarest minerals, but late in 2005 new discoveries near the Mogok Stone Tract (Ohngaing and Wetloo Mines, near Kyauk Pya Tart) raised the number of known specimens from a couple of dozen to a couple of thousand, counting all the bird seed fragments.  Needless to say, this was big news to dealers (most notably, Bill Larson), and collectors of this "Holy Grail" of species eagerly paid exacerbated prices for even dinky little specimens.   Only a few specimens weighed more than one ounce, and initially these commanded prices in the thousands of dollars.  
      For further reading, I recommend two superb articles about painite by George Rossman (Rossman et al. [1]) and Vincent Pardieu (Pardieu et al. [1]).  Together, they give a comprehensive overview of everything from history and geography to gemology and chemistry.   [Links to be provided - all articles referenced Google up easily!]  
 
       What interested this corundum collector was that a small fraction of these new specimens had druzes or crystals of ruby attached.  A superb example with gem ruby crystals both attached and included, acquired from Siggi Ellenberger in 2006, appears on the left.  In another specimen (right image,; donated to our collection by Bill Larson), painite seemed to have altered to ruby!  Since the ideal chemical formula for painite is CaZrBAl9O18 and that of corundum is  Al2O3, the association and the alteration were not great surprises.  

    

Painite with ruby Ruby pseudomorph after painite
 
 
This matrix specimen (left)  is a superb study piece, obtained from Siggi Ellenberger.
 
      Spectrographic analysis of painite specimens and geological site work have led to some understanding of their genesis and the environments where they formed.   Skarns (in this case, contacts between calcite and leucogranite) proved conducive to formation of painite; and where these occurred in ruby localities (Wet Loo and Namya , both in Burma), the association was  found.  The Wetloo Mine, near Kyauk Pya Tart, is perhaps the most notorious (see Rossman [1], Pardieu [1]).  Thus, it appears rubies can form in skarns - an interesting new observation (George Harlow:  Harlow et al. [1], and pers. conv.)!  
 
Painites, and a sapphire...
    A colleague who frequently goes to Burma found some very large (relatively speaking) specimens, which he purchased from the monks at the Kyauk Pya Thart Monastery    In all, there were well over 100 specimens (left image shows some of them).  Among them were a doubly terminated painite crystal (no rubies) weighing more than 500 carats and a huge corundum after painite pseudomorph weighing nearly 900 carats  (right images).  

 Painite crystal

 

Corundum after painite

 
        After selling a few for the owner, we struck a deal for the rest of them.  I have been asked if some would be sold, but for now we are keeping the collection intact.  My two favorites are below.   
 

    

 The one on the left  is 3 inches long, and it weighs about 180 grams (900 carats).  The other (right) is a cluster of lustrous, ruby encrusted painite crystals on a base of massive ruby corundum.  It measures about 3-3/4" by 3-1/4" by 2", and it weighs about 456 grams (2,280 carats).   Even if the painite is ignored, these are lovely ruby cabinet specimens! 

 
        In the past several months, very little painite has been found, and there are geological reasons to believe the  deposit near Kyauk Pya Thart has been "mined out".  It will be interesting to see whether  history sees these rarities as historically significant or merely as curiosities.   
     
     
 
     To he right is a superb Burmese octahedral corundum after spinel pseudomorph from the Ed David collection, obtained through the efforts of Rob Lavinsky (a nice companion for the Viet Namese octahedron on the Home page).   Contrary to a rumor which may be circulating, it is not an oo aa bird egg.    
 
 
Ruby druses are rare, but this one from Spider Mountain, Mogok Stone Tract, Burma is superb (ex coll. Bill Larson).

 

 
 
Gem ruby crystal from the Dat Taw Mine, Mogok Stone Tract, Burma, showing wavy lines which often characterize Burmese corundum.

 

 
 
Gem lilac crystal from the Dattaw Mine, Mogok, Burma

 

 
 
Unique pyramidal point of gem corundum resembling smoky quartz in body color, covered with a white druse of as yet undetermined composition (probably corundum or spinel); from Baw Mar, Burma.

 

 
 
Gem complex, multiply terminated and multicolored crystal from the Dat Taw Mine, Mogok, Burma.

 

 
  Mong Hsu terminated ruby crystal with a blue sapphire core.