Stilbite on Pargasite
Posted by: macadmin on 05.14.2020 | Filed under:

Stilbite on Pargasite

Specimen # 100890
Mineral: Stilbite on Pargasite
Location: Stilbite, Diamonkara, Bendougou, Kayes Region, Mali
Size: 4.6 x 4.4 x 4.2 cm


Detailed Description

This is a very cool, different specimen from this find. The hemisphere of deep golden yellow stilbite crystals sits as a crest on top of a mixture of deep green pargasite crystals intergrown with stilbite crystals. The surface of the stilbite ball is more uniform than many others from here, in that there is less separation of crystal groups and less “topography” – it’s not smooth, but individual crystals are not as defined. This stilbite is of the best colour. In very good condition, there is a bit of chipping in spots, mostly at the periphery. A stand-out spash of colour in the display case, a great piece.

Please note that although the dark green amphibole was labelled pargasite, I am not certain as to the extent of analysis that has been done on this material. In the Mineralogical Record article on these localities by Rock Currier and Demetrius Pohl (May-June 2011, 42:3), the authors indicate that the amphibole was confirmed by Raman specrtorscopy to be high in sodium and therefore in the pargasite range of composition. However, I am unclear as to whether further confirmatory analysis has been completed since the date of publication.

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About These Stilbites

These beautiful yellow stilbite balls from Mali made their debut at Ste. Marie 2014. Although there has only been a small trickle of fine specimens since then, the deposit at Diamonkara has once again produced a number of very fine pieces. As in 2014, moderate-to-significant damage was almost ubiquitous, and high-quality specimens like the ones in this lot are very uncommon. As a side note, although there has been a push to sell these as specimens of stellerite, none of the analytical work done to date has confirmed any stellerite identification, to my knowledge (and I am aware some analytical work has been done).

As for the specimens themselves, the good Diamonkara pieces are absolutely some of the nicest and most distinctive stilbites I’ve ever seen from anywhere, with beautiful colour and form. They are perhaps not yet appreciated for what they are – these are striking, colourful display specimens of a mineral that is often pale and drab.

Additional information

Dimensions 46 × 44 × 42 cm