This specimen is from a find that produced khomyakovite, manganokhomyakovite and ferrokentbrooksite (all verified via WDS). However, most crystals were found to be zoned with ferrokentbrooksite cores and khomyakovite or manganokhomyakovite shells – or just plain ferrokentbrooksite alone. It is impossible to distinguish the various possibilities visually.
Qualitative EDS scan for three other specimens from this find all show the presence of W. The W peak did not look very impressive, but, according to the analyst, the high energy peak of W is relatively hard to detect with his equipment, so it is actually “significant”. (The low energy W peak is “buried” under the Si peak.) If the W is in the proper structural site, and there is enough of it, this could be khomyakovite. If not, it is probably ferrokentbrooksite. EDS is not sufficient to decide. WDS – very expensive – would be needed. Khomyakovite is extremely rare. Ferrokentbrooksite – not so much.
Of the half dozen or so specimens from this find which I was fortunate enough to have properly analyzed (WDS), about half had khomyakovite or manganokhomyakovite, the rest only ferrokentbrooksite. If you think of this as a lottery ticket, that’s pretty good odds. But it isn’t a guarantee, and this particular specimen did not get an EDS scan.
The specimen features a couple of small, but well formed, crystals. You will need 20-30X to view them clearly.
The close-up photos (FOV 2.1 x 2.1 mm) shows the best, most complex, crystal (ca 0.85 mm) in front. Another crystal is partly visible behind it. There is one more, badly broken, crystal on the specimen. Qualitative EDS for the little green prisms (on another specimen) suggests an amphibole in the actinolite-tremolite series, but such scans can’t be used for a definitive ID. In any case, these crystals are very tiny. The white blades are a feldspar, probably albite.
Single item shipping weight (with MM case) is 2.8 oz.
Within the USA, postage for total weights up to 13 oz ranges from $4.25 to $6.50 (including packing etc) regardless of destination. Above 13 oz, I will use “own box” Priority Mail. The rate, including packing, varies by destination from $7.25 to $9.50.
