Fluorapatite
Posted by: macadmin on 04.18.2020 | Filed under:

Fluorapatite

Specimen # 100575
Mineral: Fluorapatite
Location: Cerro de Mercado, Victoria de Durango, Durango, Mexico
Size: 5.8 x 5.4 x 5.0 cm
Specimen # 100575
Mineral: Fluorapatite
Location: Cerro de Mercado, Victoria de Durango, Durango, Mexico
Size: 5.8 x 5.4 x 5.0 cm

Description

Detailed Description

This specimen features a super sharp 1.8 cm yellow-green gem fluorapatite crystal with excellent transparency and brilliant lustre. At certain angles there are bright rainbow-coloured glows from inside the crystal where there is some internal crazing. The crystal is nestled among quartz crystals and hyaline opal which lined an open cavity. In exceptional condition – you can find a couple of tiny edge chips with magnification if you go searching. There are two very interesting surface features near the base of this specimen – they are fully crystallized and appear to me to be etching remnants – very cool. There is a similar sized fluorapatite crystal on the back – nice in its own right, but the one on the display side is special. This is one is a killer.


About These Fluorapatites

 

Crystals of yellow-green fluorapatite from Cerro de Mercado have been known for a long time, and at times they have been produced in abundance. However, truly fine specimens are actually hard to find, as most of the fluorapatites from the mine are badly damaged. In part this is because they have typically been collected in the past without due care (tossed into buckets and so on). But in part it is also due to their own formation history – although their geological origin is still a matter of uncertainty, the crystals always have one termination and one incomplete end (doubly-terminated crystals are not known from Cerro de Mercado) and they are cemented into the matrix, all suggestive of post-crystallization activity within the deposit. This cementing involves varying mineral constituents (some of which are rather unhelpful when it comes to extracting fine mineral specimens). In particular, excellent matrix specimens are very uncommon.

Cerro de Mercado is still a producing iron mine, and the fluorapatite crystals in this lot were collected this year. As contemporary mining and sorting/separation have become mechanized, and also owing to the fact that the apatite at the mine is now concentrated for its phosphate value, the preservation of fine fluorapatite crystals and matrix specimens is a greater challenge than it used to be. Damage is still a rampant problem. I selected the few fine pieces here out of a lot of hundreds of specimens, offered by a seller who lives beside the mine. Although it is likely that specimens will continue to be produced for as long as the mine continues to operate, it is also likely that fine undamaged specimens will continue to be hard to obtain.

The definitive article on this locality is Wendell Wilson’s excellent piece in the Mineralogical Record, Special Issue – Mexico VI, Vol. 42:5, Sept-Oct 2011.


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