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Identity HelpPossible Eclarite Discovery

23rd Nov 2018 01:31 UTCForest Clark

03535600016033058892783.jpg
I have recently recovered a mineral deposit in a asymmetrical piece of Quartz that was recovered as a river rock. The mineral has a silver grey luster. It is a greyish color, simular to lead, and has blackish crystals. It is fan shaped with low level hardness. It is soft and pliable but less so than gold. I have many samples of different sizes ranging from a few millimeters to 8-10 cm by 6-8 cm. I took a few photographs and included couple of coins to help scale the samples. All of my samples came from the same piece of quartz that I removed from the American River South Fork near Placerville California, Continental U.S. I did not see any other definitive minerals with these samples but there may be trace gold dust present.

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23rd Nov 2018 02:04 UTCAlfredo Petrov Manager

Interesting find, Forest, but what made you think of eclarite, as opposed to some more common sulphosalt or sulphide like stibnite?

23rd Nov 2018 03:10 UTCTed Hadley

Especially since eclarite isn't reported from California... ?

23rd Nov 2018 03:40 UTCForest Clark

-- moved topic --

23rd Nov 2018 06:43 UTCForest Clark

It was the fan pattern that first got my attention. It has a lead like feel to it and the luster was the same as in photos of Eclarite. What other more common mineral are associated with quartz that fit this description? How would I go about having this tested definitively for authentication?

23rd Nov 2018 06:45 UTCForest Clark

It wasnpt reported in Japan either until it was discovered. I don't need this to be that, I'm only interested in authentication and testing. Do you know of another mineral that fits this description?

23rd Nov 2018 07:35 UTCKeith Compton 🌟 Manager

You say its soft and pliable - molybdenite?

23rd Nov 2018 07:49 UTCForest Clark

08725630017069403153209.jpg
Looking at Stibnite, I can see that I forms in long needle like structures. I'm attaching a photo of a nugget piece that fell off the main cluster. These samples are not long tiered needle like structures indicative of Stibnite. What is really interesting about them is when you look at some of the samples from the profile, they appear to be layered like sheets one on top of the other.


01294280015653066413895.jpg

23rd Nov 2018 07:55 UTCForest Clark

Keith,

Thanks for throwing that out there. It's soft but not really that pliable. It will break off smaller chucks but not like pyrite or something with a greater hardness score. It sort of bends before if breaks if you know what I mean. None of the samples have that shield like structure of molybdenite. But thank you for giving me an alternative.

23rd Nov 2018 08:27 UTCKeith Compton 🌟 Manager

Hi Forest,


The latest photo looks more like Molybdenite to me.


In the text: Murdoch, J., Webb, R.W. (1966) Minerals of California Bulletin Centennial Volume (1866-1966) Bulletin 189, it is mentioned that, in part, for Eldorado County (where Placerville is): Broad foliated plates of molybdenite occur in a pegmatite with axinite and copper sulphides at the old Cosumnes mine near Fairplay, , Plates of molybdenite are found at Grizzly Flat, Trask reported molybdenite from the Pacific mine at Placerville.


Cheers

23rd Nov 2018 09:12 UTCLefteris Rantos Expert

There's absolutely no indication that this could be Eclarite. Eclarite is a very rare sulfosalt mineral, totally indistinguishable by sight (and also by most simple analytical tests) from a multitude of other related sulfosalts that may show exactly the same visual characteristics and habit, as well as the commoner sulfide species Stibnite and Bismuthinite. In most cases, only sophisticated chemical and structural tests will tell the exact species.

This being said, Molybdenite is indeed a good candidate for a shiny lead-grey mineral with foil-like look and structure and strong greasy feel in the hand.

23rd Nov 2018 10:32 UTCJolyon Ralph Founder

Send a piece to John Attard https://attminerals.com/x-ray-diffraction-service/ who will be able to confirm what it is with XRD for around $50

23rd Nov 2018 11:07 UTCUwe Kolitsch Manager

Lefteris is totally right.

(BTW, another vote for molybdenite.)

23rd Nov 2018 11:13 UTCPaul De Bondt Manager

Another vote for molybdenite.

23rd Nov 2018 12:55 UTCJolyon Ralph Founder

it does look like molybdenite to me also

23rd Nov 2018 15:53 UTCPeter Andresen Expert

Nice larvikite background on the last photo! I will probably visit a larvikite quarry tomorrow, and I will probably also find molybdenite. :-)
 
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