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Mineral Specimen Identification


#1

Orchid;

Can anyone offer about this amazing grayish black
stalagmite like formation? It is warts like covered with yellowish
calcite [?] crystals.


TIA
Orchid rocks
George


#2
 Can anyone offer about this amazing grayish black
stalagmite like formation? It is warts like covered with yellowish
calcite [?] crystals.
http://www.ganoksin.com/ftp/img_2609.jpg
http://www.ganoksin.com/ftp/img_2609a.jpg 

Hi George. I believe you are correct. This specimen appears to be
Calcite on Onyx. The Onyx formed as a stalagmite and then became
coated with several layers of Calcite crystals. The small crystals
forming the layers are known as drusy Calcite crystals and the
larger single cyrstals are known as “nailhead” Calcite cyrstals. I
believe a few twinned nailhead crystals might also be visible in the
photos. Twinned crystals are always interesting to mineral
collectors and twinning is fairly common in Calcite.

You did not mention any providence associated with this specimen. Do
you know where this piece came from? A mineral specimen without a
providence is like a painting with no signature. However it still
has inherent value as an expression of nature’s handywork and should
be seen and enjoyed.

Thanks for posting the pics.
David L. Smith, JT


#3

George, If you do not get your answer here, there are several Rock
and Mineral Lists at Yahoo Groups. I do not see too many cross post
to Orchid.

Please let me know if I can help, there are several mineral people
for whom I have great admiration, and can contact directly.

Terrie


#4
You did not mention any providence associated with this specimen. Do
you know where this piece came from? A mineral specimen without a
providence is like a painting with no signature. 

Thanks for the David!

All I can say is that i bought it from a brazilein exporter, so my
rough assumption is that the material is of Brazilein origin. didn’t
asked to see it’s passport…lol

Orchid Rocks!
George


#5
A mineral specimen without a providence is like a painting with no
signature. 
All I can say is that I bought it from a Brazilian exporter, so my
rough assumption is that the material is of Brazilian origin 

It is definitely of Brazilian origin and from the very south of
Brazil where the Amethyst Geode mines are located - probably Rio
Grande do Sul - or maybe even from Uruguay, as there is much
material in Rio Grande do Sul which comes across the border from
Uruguay.

If you want to see much more of the material and other great
decorative mineral specimens, plus visits to local mines, come to
the Soledade Gem and Mineral Fair 2005 in Soledade, Rio Grande do
Sul, Brasil from May 05 to May 08, 2005.

Besides what you see exhibited at the Fair, the companies will
invite you to their showrooms to see many more - and some will
invite you for a mine tour.

If any one needs a guide and translator for the show - let me know.

I sent a picture of your specimen to a friend in Rio Grande do Sul
and asked for a definite identification of the material.

Best regards,
Robert P. Lowe Jr.
Lowe Associates - Brasil
Gemstones, Rough, Specimens
Tucson Feb 1-6, 2006, GJX booth # 205
e-mail: robertplowejr-at-juno.com


#6

Robert,

You forgot to tell us what the mystery specimen was…

As for going to the fair in Soledade, I can second the motion that
it is a worthwhile trip. I have not been to the show, but I have
been to the town. I was there about fifteen years ago and I found
the area and the processors extremely picturesque and fascinating.
You would not believe the size of some of the operations !

The only daunting aspect of the trip is that it was somewhat
difficult getting there. I went from Rio to Curitiba, hence to Porto
Alegre and then, by taxi , to Soledade. It was a somewhat convoluted
trip, but all of it was highly scenic. Southern Brazil is quite
prosperous and generally more well developed than much of Brazil.
There is a strong European presence and there is also a fusion of
vaquero culture emanating from the south. Coming back we stopped on
the Island of Santa Catarina. This island is very large and
beautiful and has some of the most scenic coastline in Brazil. What
great memories !

Ron Mills, Mills Gem Co. Los Osos, Ca.