OK, this is obviously a tough one. No real clear-cut exact answers but I'm going to give Ivt number 4. It's actually Manganvesuvianite but that may be splitting hairs. So...
Only two left! Hope you get them before I go to bed.
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Joined: Sun Oct 16, 2005 12:22 pm Posts: 21602 Location: San Francisco
Just a wee thought.
Perhaps using some of the clues would help.
Example
Stone number 1 has an R.I. of 1.63 and it Uniaxial Negative.
That means it couldn't be Topaz because topaz is Biaxial Positive
Couldn't be Fire Opal
Couldn't be sapphire
Couldn't be a variety of feldspar
I've never heard of haukite
Couldn't be clinohumite: Biaxial positive
Perhaps checking some of the guesses against the properties of the stones might be a good idea
Thank you, Barbra. Once or twice I typed similar thoughts but it sounded preachy so I didn't post them (usually when I get preachy I'm wrong!).
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Spinel is SR (this one is DR U+).
Benitoites RI is in the 1.76 to 1.80 range (this one is 1.52).
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Joined: Sun Oct 16, 2005 12:22 pm Posts: 21602 Location: San Francisco
SR means singly refractive Like garnet and spinel.
They are both cubic crystals.
Uniaxial crystals will be in the
tetragonal. hexagonal or trigonal systems
Last edited by Barbra Voltaire, FGG on Sun Nov 26, 2006 8:34 pm, edited 1 time in total.
Sorry. SR means singly refractive. I have to admit these two are pretty hard (2 more than 1). I suppose if you don't have the information available your only recourse is to guess.
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MoDo, these should be rare enough for you (if not, you can WIN!!) but:
1) Scapolite tops out around 1.58 in RI (#1 is 1.63)
2) Apatite is around 1.63 for RI (#2 is 1.52).
_________________ Information is King. Bill Wise Gemology Tools Professional http://www.gemologytools.com (if you use a Windows machine) http://www.gemologytoolsonline.com (if you use a Mac or iPad)
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