Gypsum

Origin: Manhattan, Nye Co., Nevada, U.S.A.
Owner: Lou Perloff
Microscopic image
 
Origin: Cornwall mine, Cornwall, Lebanon Co., Pennsylvania, U.S.A.
Owner: Lou Perloff
Microscopic image
 

Photo courtesy of: 

Lou Perloff

Photo-Atlas of Minerals

 

 
Origin: Sclaigneaux, Belgium
Owner: Axel Emmermann
Sample size: 3 mm across
 
Gypsum under LW-UV light
Origin: unknown
Owner: Richard Loyens
 
A small amount of calcium is often replaced by strontium in Gypsum. This causes the mineral to fluoresce white or greenish white in many cases.
 
Gypsum under LW-UV light
Origin: Winnepeg, Manitoba, Canada
Owner: Axel Emmermann

The fluorescence is probably caused by crystal defects due to the partial replacement of Ca by Sr in a 200:1 ratio. The fluorescent hourglass is most likely the result of strontium atoms having a greater affinity for two opposing faces during crystal growth. The crystal defects are thus stacked in a pyramidal form following the growth of those two faces. Stereo photo under short wave UV.

Origin: Le Forest, France
Owner: Axel Emmermann
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    • Photo courtesy of: 

    Axel Emmermann

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    Selenite with phantom
    Origin: Platosa Mine in the Sierra Bermejillo, 20 km from Mapimi, Durango, Mexico
    Sample size: 13.5 x 1.5 x 1.25 cm
     
      
    Gypsum pseudomorph after calcite with melanterite on sphalerite
    Origin: Mid-Continent Mine, Picher, Oklahoma (old "Tri-State District"), U.S.A.
    ex. Edward Swoboda Pseudomorph Collection
    Sample size: 7 x 5 x 4.5 cm
     
      
    Origin: Cave of Swords , Naica, Chihuahua, Mexico
    Ex. Marty Zinn collection
    Sample size: 36.7 x 7.2 x 3 cm
     

    Photo courtesy of: 

    Rob Lavinsky

    The Arkenstone

     

      
     
      
     
      
    Origin: Las Salinas halite mine, near Otume Village, south of Pisco, Ica Department, Peru
    Sample size: 4.5 x 5 x 7 cm (top/2nd row)), 8.5 x 6.5 x 7.5 cm matrix, crystal 4.5 cm (3rd row), 12.5 x 11 x 5.5 cm (bottom)
     
    Gypsum on calcite
    Origin: Wilson Ranch, Elk Creek, Meade Co., South Dakota
    Sample size: 31 mm wide
     

    Photo courtesy of: 

    Dan Weinrich

    Dealer in fine mineral specimens

     

      
      
    Selenite on a bed of very small yellowish calcite crystals
    Origin: Marocco
    Ex. Giorgio Spiga collection
    Sample size: 10 x 8 x 3 cm
     

    Photo courtesy of: 

    John Veevaert, Trinity Mineral Co

    Trinityminerals.com

     

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