Hello Teevee
Sorry, but when you said, "Many type II kimberlites have outstanding Calcium VS chrome garnet plots and are very low grade or barren", that sounded to me like "type II kimberlites are typically not economic".
Now I am really confused. Perhaps this was just a typo, but did you mean to say "low in Ca and high in Cr (towards J-1)"? All G-10's are high in Ca and Dave indicated that it was J-10's that were high in Cr. Which is it? Are J-1's or J-10's high in Cr? Are J-1's lower in Ca than J-10's?
I will try to track down the paper you refer to. Any idea where I can find that journal?
In the interim, I would invite you to read Age, Origin, and Emplacement Of Diamonds: Scientific Advances in the Last Decade. Melissa B. Kirkley, John J. Gurney, and Alfred A. Levinson.
Dr. Kirkley was a post-doctoral research officer, and Dr. Gurney is a professor in the Department of Geochemistry, University of Cape Town, Rondebosch, South Africa. Dr. Levinson is Professor in the Department of Geology and Geophysics, University of Calgary, Alberta, Canada.
You will find the paper reprinted in Gems & Gemology, Vol. 27, No1, p.p. 2-25
Thanks again and regards
P.S. Thanks Fix. Glad you enjoyed the discussion. Nice to have a thread where this can be done without all the nonsense and flaming.
Regards |
