Olivine? green Tourmaline? Any ideas

[jewelerdave]

Over last summer while gem hunting in Wyoming following some leads I was found on some private property and asked to leave but then asked to Id some things when they found out I was a jeweler.

The ranch hand asked if I could Id something for him he found, I said sure. he told me of a rock covered in Green Crystals and didnt know what it was.
He went back to the ranch house and came back with this rock.

I was able to take a couple pictures of a weird specimen that the local ranch hand had found.

Problem, I am not sure what the heck it is.

The country rock is just a quartz/feldspar granite.

First I thought maybe an olivine or tourmaline. Probably a massive olivine but I want to see what others have to say.
This area has had in the last couple years discoveries of Ruby/Sapphire, Iolite and quite frankly nothing would surprise me from this area that I would not otherwise consider.
Just in the last 10 years new gem deposits in Wyoming have been ruby/Sapphire, peridot, iolite, diamond, Chrome Diopside and the list just keeps growing.

 

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[MEinWV]

My guess would be .........Epidote

That was my first thought just looking at the pic and then I found info from Wikipedia.

Epidote....... IMO

 

[Old Dog]

Looking at the chrystal form and habit in the second picture I concur
Epidote

In the coagulated solid state of this rock Epidotite.

This form of Epidote is most famously from Chaffee County Colorado.

Thom

 

[jewelerdave]

Probably right, I have Emailed a couple others and they say it may be epidote too. unfortunately I dont have the specimen to show.
Thanks for the ID help, its a cool specimen especially for Wy

 

[USTiger]

I am not an expert but i do have this info on Epidote

Name : Epidote
Chemistry : Ca2(Al, Fe)3(SiO4)3(OH), Calcium Aluminum Iron Silicate Hydroxide
Uses : As a gemstone or as a mineral specimen
Color(s) : Color is green to yellowish or brownish green, also brown to black
Hardness : 6.5 - 7
Specific Gravity : 3.3 - 3.5
Crystals : Monoclinic
Accompanied By : Feldspar, quartz
Similar To : Tourmaline.

Epidote is the principal member of a group of silicate minerals that occur most commonly inlow-grade, calcareous metamorphic rocks and also in igneous rocks,where they have altered from feldspar, pyroxene, and amphibole minerals. A calcium aluminosilicate, epidote forms pistachio-green to dark-green elongated crystals (monoclinic system), disseminated grains, or fibrous or granular masses that have perfect cleavage in one direction.

Epidote is a structurally complex mineral having both single silicate tetrahedrons, SiO4, and double silicate tetrahedrons, Si2O7. The formula of epidote could be expressed in a such a way so as to reflect this organization; Ca2(Al, Fe)Al2O(SiO4)(Si2O7)(OH). The two aluminums represent the parallel chains of AlO6 and AlO4(OH)2 octahedra that are the heart of the epidote structure. The silicate groups and extra ions connect the chains together. Since the chains are parallel, the crystals tend to be prismatic. The chains are arranged in parallel planes and the perfect cleavage breaks the bonds between these planes. Luster is vitreous.


Hope it helps.

USTiger