Beth,
Nice crystal! I love odd-ball crystal forms in any mineral.
Diamonds come in a wide variety of forms, usually based on cube and octahedron, but other forms are found such as tetrahedron, trisoctahedron, hexoctahedron, and others. Hopper crystals are indeed known. I don’t know if there is any special terminology applied to hoppered diamond crystals. The hoppering can be intricate and crazy.
The form you have is notable in having a square in the center of the face that is rotated 45 degrees from the cubic faces. When you want to check on crystal forms the best source is the monumental work by Victor Goldschmidt published in nine volumes in 1916, Atlas der Krystalformen. I don’t have that myself, but John Betts has all of the diamond pages from the Atlas on his website (http://www.johnbetts-fineminerals.com/jhbnyc/diamdiag.htm) and for other minerals as well, such as fluorite.
I copied these four forms (attachment) from there. They are the only ones having that square in the center of the faces. There are X-shaped striated bars with striations parallel to that square. Figure 195 seems most like yours. It is the only one of the four in which the bars are diagonal to the cubic faces, like yours. Obviously, there are differences from yours, however. I think if Goldschmidt had been aware of such a form it would also be in his Atlas.
Congratulations on that nice find!
Edited 1 time(s). Last edit at 02/14/2012 01:41AM by Norman King.
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