Density of various stones | Forum — The Modern Antiquarian

handofdave Jul 13, 2007 12:42:24

I've noticed pronounced differences in the weight of the larger stones I've moved into my wife's flowerbeds. Granite seems much more dense than an equivalently sized chunk of sandstone, for example. Anyone have a link to something about that?
I've got a new appreciation for the old neolithic builders. We lugged a very heavy (I was JUST able to lift it, barely) 3 foot long, 1 foot wide, 10 inch deep wedge of granite home from Maine. I'm trying to scale that up in my mind to the really big stones people have raised. Impressive!

Spaceship mark Jul 13, 2007 12:54:43

Replying to handofdave

Granite's quite light compared with, say, Basalt. As a result you weigh less in Cornwall than Iceland as the the amount of Earth excerting a gravitational pull is less over less dense rock.
Both have a pretty solid crystalline structure so are still fairly dense, wheras sandstone has more voids in it, ie is more porous (though not necessarily permeable). Because more of it is air it's lighter.
Most rocks are still pretty darned heavy if they're big enough though...
(That's the first time I've used anything from my Geology degree in ages!)

Hob Jul 13, 2007 19:08:48

Replying to handofdave

Definite sympathies. I've lugged many a rock to our garden over the years, and I've learned to be suspicious of one particular kind of rounded boulder that is common in Tyneside. On the surface, they look like sandstone, so you think 'Oh, no problem' but they're preposterously heavy (which is why they're still lying about). When you try to carve them, it turns out that the sandy bit is a weathered patina only an eighth of an inch deep, and inside is a fiendishly dense grey stuff, very heavy and a right bugger to carve. Wish I knew what it is.

I know it's easy to become blaze about megalithic stones, when you've seen bigguns, smaller ones become nowt special. Then you try and shift a small one a short distance by yourself, and suddenly, respect blooms anew. If nothing else, for the evident community requirement when it comes to shifting even moderately big old rocks.

Good on yer HoD, it's a noble calling, and disparagement from the spouse goes with the territory ;)