MICRO  FEATURES

 

     This page is devoted to inclusions and those other features of corundum mineral specimens and gemstones which are best observed under magnification.  I am greatly indebted to friends and colleagues for their generous permission to present their work, creating this page for all of us to enjoy.
     Please note that there may be copyright restrictions on these contributions, which must be respected.  Publication here does not in any way compromise the rights of the owners of  this intellectual property.  If you desire to reproduce any of these items, the owner should be contacted directly for permission.  "The Corunduminium", however, does not impose any additional restrictions on their use.
    
1John Koivula Inclusion Photos John Koivula, Chief Research Gemologist with the Gemological Institute of America's Gem Trade Laboratory in Carlsbad, California, has submitted the following photomicrographs of inclusions and other microscopic features of ruby and sapphire gemstones.  They show another aspect of the beauty and fascination of gem corundum which cannot be enjoyed without special equipment in the hands of a special artist.  This is a unique gift, presented for all of us to share, and John has also hinted that every now and then there might be more!  Thank you, John and GIA, for allowing this unique opportunity!
    Please note that certain copyright restrictions apply:  they are not to be downloaded, otherwise reproduced, or used in any manner for profit.  John's remarkable book, "Photoatlas of Inclusions in Gemstones", co-authored with Dr. Edward Gbelin, may be purchased from the GIA Bookstore in Carlsbad through the GIA website, www.gia.edu.
    John's captions are given here alongside the corresponding thumbnails, which you may click on to see the full resolution photos.  Enjoy!
Ruby1.jpg (129621 bytes) Ruby 1:  Polysynthetic (lamellar) twinning showing the two dichroic colors of ruby in a natural untreated ruby from Thailand. Magnified 15X
Sapphire 1:  Growth zoning in an untreated natural Kashmir sapphire.  15X Sapphire1.jpg (202483 bytes)
Sapphire2.jpg (260061 bytes) Sapphire 2:  Rutile and apatite crystals in a natural, untreated sapphire from Rock Creek, Montana.  25X
     Ruby 2:  Corroded protogenetic calcite crystals in an unheated natural ruby from Mogok, Burma.  20X Ruby2.jpg (150678 bytes)
Ruby3.jpg (217155 bytes) Ruby 3:  Partially healed thin film crack decorating a parting plane in a Thai ruby.  80X
Sapphire 3:  Bright red crystallites of uranium pyrochlore in a sapphire from Pailin, Cambodia.  25X Sapphire3.jpg (151484 bytes)
Sapphire4.jpg (167164 bytes) Sapphire 4:  Garnet inclusion in a sapphire from Songea, Tanzania.  10X
Ruby 4:  Damaged primary fluid inclusion in a heat-treated ruby from Madagascar.  20X Ruby4.jpg (166088 bytes)
Sapphire5.jpg (235017 bytes) Sapphire 5:  Typical formation of epigenetic rutile needles in a natural untreated sapphire from Sri Lanka.  20X
Ruby 5 Rutile crystal with a dislocation "comet tail" in an untreated ruby from Madagascar.  35X Ruby5.jpg (154659 bytes)
Ruby 6Both fresh and altered pyrite inclusions in a natural, untreated ruby from Kenya.  15X
Sapphire 6:  Sub-metallic rutile prisms in a natural, untreated sapphire from Colombia.  20X
ChathamRubyPlatinum.jpg (58335 bytes) Ruby 7Platinum inclusion in a Chatham Created flux-grown synthetic ruby. 20X
Sapphire 7Platinum inclusion in a Chatham Created flux-grown blue synthetic sapphire. 20X ChathamSapphirePlatinum.jpg (71515 bytes)
 
2Work of Feng-Ming YenFeng-Ming (Alan) Yen, a Gem enthusiast from Taiwan, took these photographs of inclusions in sapphires.  Though they are not formally copyrighted, he requests that they are not reproduced or used for profit without his permission. 
He sent  three pictures of inclusions in Kashmir sapphires from his personal collection along with the remarks which follow in quotes.    A positive determination of the composition of these inclusions has not yet been made.  The yellow color in the first is due to the field illumination.
" ... 2 pictures with uraninite inclusions, I believe, one has a few zircon crystals with uraninite crystals embedded and the other has stress fracture which (resembles an) octahedron."  [Note:  Compare John Koivula's Cambodian "Sapphire 3" above, which has uranium pyrochlore inclusions.  This may be a useful distinction for origin determination.]
"The third picture ..., under 400X,we can see silk like Ceylon or Burma, but much finer ..."  [Note:  Only the lines in direction 10:00 are silk - the thicker lines in the direction 11:30 are striations left from the faceting and polishing.]
     The pictures below show minerals attached to small Kashmir sapphires, which may be heat treated but we are not sure.  The crazed greenish to brown material is being called "melted tourmaline", but its chemical composition has not yet been ascertained.  What do you think?
 
  We welcome the comments or opinions of our viewers on these observations.  Contact me at wheierman@corunduminium.com or Feng-Ming at fmyen@gcn.net.tw.
 
  3Vincent Pardieu PhotographsVincent Pardieu is a French Gemologist living in Southeast Asia, who is particularly fond of  Mogok, Burma.  He sent the photos below, showing as yet unidentified blue crystalline inclusions in Burmese rubies.  The last photo shows the ruby crystal immersed in a fluid with nearly the same index of refraction as the corundum.  
 
 
4 Dick Berg's Scanning Electron MicrographsDick Berg, Senior Research Geologist, Montana Bureau of Mines and Geology, took the following SEM's as part of his research into the formation of Montana sapphires; and he has graciously provided them for our enjoyment here.  They are not copyrighted, and may be copied with appropriate credit to the source (Dick Berg), but may not be or used for profit in any manner without his expressed consent.

1:  Sapphire from the Rock Creek (Gem Mounatain) deposit, west of Philipsburg, Montana.
2:  Sapphire from Eldorado Bar on the Missouri River, northeast of Helena, Montana.  
3:  Sapphire from the South Fork of Dry Cottonwood Creek (northwest of Butte) showing fresh fracture.
4:  Sapphire from South Fork of Dry Cottonwood Creek showing grooves developed along parting planes.
5:  Sapphire from the South Fork of Dry Cottonwood Creek showing surface texture and grooves developed along parting planes, both features typical of sapphires from this locality.
6:  Sapphire from the Yogo deposit in central Montana, showing trihedral forms.
  5My Own Closeups:  I do not yet have the right equipment for this, but these crystals are so doggone interesting I thought you might like to see some of my first puny attempts to record what you can see under the microscope.  Look for these to be replaced by better ones before too long.  Enjoy!  (4/9/04)  
  Two Yogo Gulch, Montana sapphires with prominent surface etching and "pits" suggesting partial resorption in situ.  Both are about 3/8" in diameter.  
  These two "Yogos" show very unusual pitted and layered  surface textures (loaned by Amos Knapstad, Yogo Creek Mining)   .
  Three neat Montana sapphires, given by Marc Bielenberg to Louis Zara (obtained from his estate).  The two on the left are from Dry Cottonwood Creek, and the one on the right is from Rock Creek.
 
  More Yogo shots:  On the left are my two favorite violets.  On the right is one with some neat inclusions (black tourmaline?)
  Mong Hsu, Burma produces some wild rubies!  On the left are gem crystals with dark blue sapphire cores, the smaller  about the size of rice grains.  On the right are "puffed rice" size heat treated "trapiche" rubies (untreated crystals are often almost black).  
 

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