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Identity Helpamethyst geode and ?

6th Jan 2010 23:12 UTCMike Royal

pretty sure this is from brazil but the globular matter in the center last pic could this be prehnite a needle scratched it but fingernail didn't thanks for your help mike

6th Jan 2010 23:16 UTCMike Royal

size is 76 x 92 x 43.5 mm and the things in last pic are 12 and 7.25 mm across hope this helps

6th Jan 2010 23:21 UTCDana Slaughter 🌟 Expert

Hi Mike,


It looks like one of the geodes from Chihuahua State, Mexico with some goethite-included calcite crystals in the center.


Dana

6th Jan 2010 23:25 UTCMike Royal

could be got it from estate sale in Arizona thanks dana mike

7th Jan 2010 16:29 UTCSpencer Ivan Mather

Goethite included calcite?


Spencer.

7th Jan 2010 18:17 UTCRob Woodside 🌟 Manager

My first thought was on seeing first two was goethite and not from Barzil. The last photo shows the "goethite" is not the least metallic or opaque, so I would tend to agree with Spencer.

8th Jan 2010 12:30 UTCRock Currier Expert

It appears to be an agate geode from Rio Grande do Sul State in Brazil. The minerals that grow in these geodes are few. It would appear that perhaps the crystals that are growing in the geode may be calcite crystals. A drop of acid on one of them would confirm this if the acid caused a bubbling reaction. It looks as though it may have already suffered some etching either naturally in the ground or by someone at the source having cleaned it up with acid.

8th Jan 2010 13:39 UTCDana Slaughter 🌟 Expert

Hi Rock,


To me, the rind looks exactly like those from Chihuahua. I had a few of these, virtually identical down to the included-calcite crystals, that I got from an old collection in Michigan. The couple bought burlap bags filled with these Mexican geodes and never got around to cutting them all---to me, the rind and the lenticular included-calcites suggest Mexico.



Best regards,

Dana

8th Jan 2010 14:37 UTCSpencer Ivan Mather

Hi Dana, It deffinately looks like that is came from Mexico, the outside of the geode looks exactly like the outside of the agates from that locality?


Spencer.

8th Jan 2010 14:45 UTCAlfredo Petrov Manager

To me too it looks more like a mexican than a brazilian geode.

9th Jan 2010 00:05 UTCCraig Mercer

I agree, definitely a Mexican geode with Calcite.
 
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