# Is granite useful for precious metal extraction?



## boutselis (Jun 17, 2012)

Is Granite useful in any way? I am getting ready to throw some out and thought I would check just in case. I have a few 2ft square pieces of counter top about 1+1/2" thick. 

Wasn't sure If I would be doing some grinding / pulverizing or if it could be used in melting or processing?


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## Lou (Jun 17, 2012)

Great to put hot things on or to set a balance upon and dampen vibrations that would throw off the scale.


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## Harold_V (Jun 18, 2012)

In keeping with Lou's comments about granite being great to put hot things on----don't put overly hot glassware on granite. The thermal shock can cost you the vessel. 

Harold


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## Lou (Jun 18, 2012)

That is the truth. 

Only for metal incineration pans or quartz ware should it be done.

Glass and most ceramics--put that onto a kaowool blanket! It also doesn't help that granite is hard stuff, so some glass is just lost by attrition.


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## Barren Realms 007 (Jun 18, 2012)

Put some cloth over the granite before you put your hot vessel on it, like a pair of cut off pants leggs.


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## Geo (Jun 18, 2012)

i ounce placed a hot pyrex loaf pan i was force drying gold powder in, on a couple of folded paper towels. a few seconds later and the pan exploded (for lack a better word). it didnt break or crack, it flew apart with a very loud POP.


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## boutselis (Jun 20, 2012)

Geo said:


> i ounce placed a hot pyrex loaf pan i was force drying gold powder in, on a couple of folded paper towels. a few seconds later and the pan exploded (for lack a better word). it didnt break or crack, it flew apart with a very loud POP.



Are you saying the paper towels had something to do with that? I'm wondering why there are not more exploding pyrex in the kitchen.


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## jimdoc (Jun 20, 2012)

Newer Pyrex is made in China, and they don't make it the proper way. They use a shortcut to save money that has Pyrex items exploding on people. You can Google that. There should be laws to keep people from buying trusted brands and changing things that affect the safety of those items. Never trust any glassware made in China, at least run heating tests without acids and precious metals involved.

http://www.snopes.com/food/warnings/pyrex.asp

http://www.consumeraffairs.com/news04/2008/08/pyrex.html

Jim


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## NobleMetalWorks (Jun 20, 2012)

When I first started, I bought used 800 ml beakers off eBay. I purchased 8 used, they were all suppose to be Pyrex. One was not and I had issues with it.

I had dissolved sodium nitrate on a hotplate/stirrer with mild heat so that the sodium nitrate dissolved but was under the boiling point. I was being mindful of the possibility of thermal shock, I used a bit of sand on the hotplate, I even prepared a place to set the beaker down on, with sand also. About 30 seconds after I removed it from the hotplate, and set it on a ceramic plate that had a little sand on it, it broke. Shattered. Similar to what Geo described. The problem wasn't with what I prepared for thermal shock, the problem was the ice cold air blowing into my garage, and right directly across where I had the beaker.

Sometimes it's not what you set it on, it's the temperature of the air...

Scott


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