GeologyRocksAnother hello!
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Hello Dustin and welcome to
Mon, 05/13/2013 - 08:58Hello Dustin and welcome to GR.
We will certainly give you all the help we can, but please remember that this isa British site and we only know the geology of the US in the broadest terms. We would need information on the local geology to help us identify your pictures.
Couple of other points. Always have something to show the scale of your picture. With a general rock formation a person included in the photo gives us an idea of how big the thing is we are looking at. With a hand specimen, a coin or tape measure (an every day object) will give the same indication.
To illustrate that on one course we were shown two very similar pictures. We said both were volcanoes taken from space. They were very symmetrical. One was a volcano viewed from space...... it was Mt. Fuji taken from the ISS.
The other was a pingo (sometimes called a hydrolaccolith) -only about a 10 yards across and taken from a low flying aircraft. Had us fooled.
With hand specimens we need to see detail. Blurry pics are no good.
Knowing the Specific Gravity (now known as Relative Density) helps enormously. It is far from an exact science at this stage. Just look at the size and judge the weight against the same volume of water. Terrestrial rocks will normally be around 2.7, whilst oceanic rocks tend to be around 3.3 Minerals will vary enormously. Pyrite and fluorite will be around 5ish. Lead (galena) will be 9. Gold will be about 12, and platinum will be 20 or so. Its the same for meteorites. Stony meteorites will be 3ish. Fe-Ni (iron-nickel - the valuable ones!) will be about 7-8.
Hardness is another important clue. Rather than write it all out I suggest you Google 'The Mohs Scale of Hardness' It should tell you all you need to know.
Lets take it from there. But be warned - you might get hooked on geology!
John
“Civilisation exists by geological consent, subject to change without notice.” - Will Durant
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Another hello!
Submitted by XenoStuff on Sun, 05/12/2013 - 14:37.Hello all! My name is Dustin, and I'm from Ohio in the US. I'm not really a geologist, but one that enjoys the aesthetic beauty that rocks contain, especially when broken open. I'm hoping it's ok to post pics and asking what type of specimin I have. I plan on categorizing and memorizing them so I can learn what to look for when out rock hunting.
Anyways, it is nice to be here and I hope to contribute, in the positive, to the conversations that take place.
Cheers - Dustin