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 Home / Gem Library / Natural Gemstones / Jeremejevite July 19, 2018  


Natural Jeremejevite
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There are 2 Jeremejevite(s) available at Multicolour.com


There is little available information about this rare mineral with a strange name. I came across this interesting article by Christopher L. Johnston - Omaruru, Namibia, which I have copied in its entirety below.


Known Facts
Refractive Index: 1.64 - 1.65
Chemical Composition: Al6B5O15(F,OH)3
Hardness: 6.5 - 7.5
Density: 3.28 - 3.31
Crystal Group: Hexagonal
Ocurrence: Mile 72 by Khan River, Swakopmund, Namibia; Soktujberg, Adun-Tchilon and Baikal, Russia, Madagascar

“The locality name may sound a little strange BUT it really IS just a mile marker in the middle of the desert, and the jermejevite-bearing pegmatite was stumbled upon only by serendipity. Originally discovered in the early 1970’s and misidentified as aquamarine crystals, it was only in the mid 1970’s that the blue crystals from Mile 72 were identified as jeremejevite (John Sampson White, Smithsonian). Previous to that, in the late 1960's, specimens of an unusual clear-to-straw yellowish elongated mineral were found at this locality by John Saul (who operates several African gem mines), although further mining was not done at that time and he apparently kept the specimens until recently when they were sold to mineral dealer Cal Graeber. Because the newly mined crystals are in fact identical to this FIRST discovery of jeremejevite in form, color, and size, we purchased the older ones and integrated those specimens with the offering of this newly mined lot. With three claimants to being the original discoverers, the true identity of the first claimant is somewhat clouded. What is known is that in 1975-1976 mineral dealer Sidney Pieters of Windhoek pegged three lode claims on the location and initiated the first large-scale recovery operation, an 18-month mining effort.

In early 1998, mineral dealer Charles Locke Key (keyite, ludlockite...) undertook an ill-fated mining effort using the original miner, Peter Kittler, who discovered "the pocket". This effort never got off the ground and subsequently, Bryan Lees of The Collectors Edge negotiated a lease agreement through his Namibian mining company, Khan River Mining & Exploration (Pty) Ltd. with Sidney Pieter’s daughter Shelly Mansfield, the current legal claim holder. In January of 1999 sophisticated mechanized operations commenced at Mile 72 by Khan River.

Within the first week of operations Khan River Mining & Exploration mined more rock then the previous operation did through its entire 18 months. Unfortunately in spite of the massive undertaking, (3500 metric tons over 13 months) just ONE SINGLE POCKET of straw-colored (these are not quite colorless!) jeremejevite was discovered. This pocket produced under 200 single crystals, only a very few at 2 cm in length or larger, and a dozen or so specimens associated with feldspar crystals (these matrix specimens mysteriously disappeared from the claim, however, and appeared for sale at the Munich show last year under mysterious circumstances). The largest single crystal produced was 46mm in length (and is available for sale on consignment from us, with Graeber & Himes, at the Denver show for $3500). This pocket is 3m below MSL.

Operations were terminated in February-March of 2000 based on mounting expenses and lack of return. The pegmatite has been largely mined out and it is reasonable to assume that further production will be near-zero.

After a considerable amount of study a possible mechanism for the paragenisis of the jeremejevite has emerged. The Mile 72 locality is at the margin of a continental rift generated +/- 540mybp when what is now South America migrated from the supercontinent. During this episode there developed a massive trench with associated turbidite sequences. In conjunction with this sedimentation, the Damara Orogeny was progressing which resulted in high-grade metamorphism within the sediments driven by the emplacement of the granitic Salem pluton. This metamorphism produced a series of chemically simplistic metamorphic pegmatites in the Mile 72 area. These pegmatites are generally sill-like but lack a source, indicating metamorphic rather than primary igneous origins. The pegmatites are coarsely crystalline and generally consists of feldspar, quartz and schorl with minor apatites, lepidolite, & muscovite micas. Approximately 100mybp the Cape Cross-volcanic event and penecontemporaneous emplacement of the Uis tin tantalite pegmatites occurred. These late stage Uis pegmatites extend to Mile 72 and it is now presumed that the jeremejevite was a remobilization crystal product resulting from the intersection of an existing Damara age metamorphic pegmatite, and one of the Cretaceous age Uis pegmatites.

As a place to mine Mile, 72 is at once of unequaled beauty and a complete back breaker. The weather is impossible; equipment rusts at a pace unrivaled anywhere in the world, and the hole itself is only fractionally above the nearby sea level.”

Article by Christopher L. Johnston - Omaruru, Namibia


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Jeremejevite
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Jeremejevite Stats/
Popularity Index: 14882hits
Total Items: 2items
Total Weight: CTS 44.98
Cheapest: USD 3838.32
Most Expensive: USD 5991.84
Largest: CTS 27.74
Smallest: CTS 17.24
Last Added: 05/14/18 06:42:36

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