Chockstone Forum

      Sponsored By
      ROCK
   HARDWARE

Chockstone Photography

Australian Landscape Prints

Chockstone Forum - General Discussion

General Climbing Discussion

Topic Date User

buying boulders 24-Jun-2013 At 12:11:24 PM Snappy

Message

On 24/06/2013 Duang Daunk wrote:
>On 24/06/2013 Snappy wrote:
>>Granite is among the more dense rock, so you would expect sandstone/trachyte
>>boulders to be a little lighter. Although then you would have to bubble
>>wrap them as they are more fragile... :)
>
>Really?
>Why is it that so many climbers think they are geologists?
>Really, I'd prefer a bland wiki reference than an uninformed opinion.
>
>I am no geo but I know that trachyte is of volcanic origin and like granite,
>dolerite, basalt and probably a lot of other rock types can be way up there
>in the density and non brittle stakes.
>Sandstone by comparison is sedimentary and that is another story.
>
>You can do the wiki thing if it has anything relevant to prove me wrong.
>
>
Unfortunately the wiki articles for other kinds of rock aren't as well layed out as the granite one. However I found this: http://geology.about.com/cs/rock_types/a/aarockspecgrav.htm
Granite: 2.6-2.7g/cm^3
Rhyolite: 2.4-2.6g/cm^3 (so a little lighter, but not as much as I would have thought).
Sandstone: 2.2-2.8g/cm^3

That doesn't give a complete picture, as the porosity of the different kinds of rock comes into play. My assumption (which you can feel free to disregard, or google, if you want) is that extrusive rock such as rhyolite would have a higher porosity than intrusive rock such as granite.