freezing rocks

[Alvin]

It sounds like when the rock gets on the surface, the worst damage has been done. The  rocks in the tidal water that I pick, not only get to be in and out of water while freezing every six hours, but get beat up in the water also. So the way I see it, once I save them from the beach, they should keep better under my care even if they are allowed to freeze when dry. That sure sounds like a real tec. job.  If you can get them to pay you for cutting the rocks too, you would have a rock hound dream job.

[gregorgr8]

I still do not understand why we would not be able to get a specific gravity - your exmple of gold, for instance, does not absorb water, yet it has a specific gravity (density that is). 

What you are doing, I think, is measuring two different specific gravities. The first one with absorbed water, and the second one without.

As I write this I think maybe this is a way of eliminating the effect of any voids in the rock by filling it with water and then eliminating it.

but still   "could not measure a sp grav"?

[mirkaba]

Maybe a part of the absorption test. Wouldn't water add to the dry weight but be weightless in water? Geez thats beecause Iuse the specific gravities of gold and quartz. I do not have to find the water displacement! I have never had to soak gold specimens before doing SG tests. Speaking of which........In 1983 I found a pocket of highgrade gold that had frost wedged out of the wall rock right at the portal of an old adit. Recovered almost 38 ozs of gold! The Old Timers missed it. 

[Charlotte]

After all the freezing, thawing, meteorites, volanic activity for millions of years I think the rocks have proven themselves to be very durable no matter what the weather is. 

[hulagrub]

Bob WOW 38 oz. What a find!!! You could have bought a house with that, back then.
     Gregor and Bob, well think about the absorption, if the water has not filled in the voids of a rock, then when you check for specific gravity, air would cause the rock to be lighter as compared to the water.
     Think about two 1 oz. pieces of agate. One is very solid, one is full of visible pits, (the key word here, visible). Now if the one is of lesser specific gravity, would it still be a type of quartz? Is it still as hard, yes? Or?

[greenhorn]

Very interesting, but I would like to point out the finding specific gravity is not reliant on a substances ability to absorb water as you initially stated.