FMF - Friends of Minerals Forum, discussion and message board

[leone86]

found this in iowa today

[Bob Carnein]

Probably quartz. Check the hardness by trying to scratch a piece of glass or steel with it (harder than glass or steel).

[leone86]

Yes! It actually cut into a thin pane of picture glass! I Was able to separate it easily after using it to, well cut it. It scratched with very little pressure steel. Steel from cnc manufacturing of Stanley infrastructures attachments aka Stanley black and decker. It is very scratch and rust resistant steel!

[leone86]

can anyone tell me the accuracy of a diamond tester on raw stones of any size really.

[alfredo]

It's not a diamond, so don't waste your money buying a diamond tester. They don't work reliably on rough surfaces anyway, they're designed for use on polished gemstone facets.

[19Kath93]

[James Catmur]

I agree, quartz. The simplest way to test hardness is to try to scratch a harder mineral and try to scratch it with a harder one. If you have an old diamond about the house, see if the diamond scratches it.

[19Kath93]

[leone86]

thank you I wasn't buying one someone already owns one and I thought it would be in accurate being a raw stone and the size it is! it registered as a diamond but I will however say it registered my sapphire at not full lights but at acceptable range. Sapphire is confirmed by expert as a raw Sapphire. it registered my diamond rings a lights instant but the raw stone in picture it isn't instant but fairly quickly. So I asked others here to validate its accuracy. I sent photo to mineralogist he said without seeing it he could not confirm nor deny it being one thing or another but sent pictures of diamonds that look very close to this one and said to use uv and normal light to see if the light retracts amd if I can see the light directly through it is definitely quarts a very beautiful sample but if I didn't see light pass directly through it very well could be one. He also said most ppl will quickly shoot it down he himself is guilty of skeptical dismay but there are a few lucky ppl who do just for whatever reason get lucky and said I might want to think about playing the lottery and staying out of the rain whatever that means! I know the odds of finding such a thing and I already am convinced its a quarts however the lack of rounding on the edges as my other samples all have unless it came directly from the source makes me wonder either way I love it! it's a great find for my collection I found these also he asked did I find any other samples i said alot and showed him my favorites he said well I'll be and I am supposed to be meeting him at a university to look at them he only asked if he could as where I collected them I told him at a fresh water spring where it comes out of the bluff in this particular place it has several conjoined springs two above ground several under I collect water Crescent from the large one the one that comes bubbling out from the base of the bluff it's amazing I grew up on that land oddly never found many rocks before but recently with rain and all that it has produced alot of rocks into the stream I could spend hours picking up rocks but I granted a few the water hurt my hand and it was already getting dark and I was in the heart of 240 acres no thanks ! I called it a night! Is it true since they came from underground spring they could actually be from anywhere and why would they just now be coming out or I suppose they could be surfacing he said from the spring bed which is changing drastically actually.

[leone86]

also the mineralogist pointed out in the first picture is why he couldn't say it wasn't this or that you can see in the right hand upper side of the picture the light retracting of it it appears to be four triangles and that any person with any knowledge of quartz or diamond would know is not a character of quartz but of diamond but that without seeing it he could not tell me it was or wasn't either or. I again just love it! It is very very cool to look at! lol. I should mention my luck is no luck so I will let you know what I'm told lol. I will definitely be laughing at myself for even considering it for one second but never found one that I 3ven thought might be in 13 yrs of collecting found actually 2 diamonds few years back brown with black inclusions dirty dirty and I was not in iowa lol.

[alfredo]

https://www.mindat.org/mesg-506598.html
Sorry, it's a bit facetious, but...

[Pete Richards]

Here's another way of thinking about this.

This is not a complete crystal with well-defined crystal faces - it is a broken part of a crystal (or several crystals).

Diamond has perfect cleavage, and the surface of broken pieces of diamond crystals shows flat reflective surfaces.

Quartz, the other candidate, lacks cleavage, and the surface of broken pieces shows what is called conchoidal fracture - it breaks like glass into curved, often scalloped surfaces.

Your specimens clearly show the latter behavior. This does not mean it is quartz for sure - it could possibly be something else, but it pretty much rules out them being diamond. And I am as sure as I can be when just looking at pictures that what you have is quartz.

Several of your pictures show specimens with different-colored parts. These are rocks composed of several different minerals, and the identity of those minerals is a different question completely.

[Bob Carnein]

Another easy test (at least for the samples that are minerals rather than rocks) is to measure the specific gravity. You can find a simple method for doing so at the John Betts Fine Minerals website.

[James Catmur]

If you want to use a less accurate, more brute force method, you can:

1) Measure the volume of the specimen with just a measuring cup.
i) put water in a measuring cup to a level higher than the size of the specimen.
ii) place the specimen in the cup with the water.
iii) measure the volume increase by how high the water rose in the measuring cup. The difference between the water volume before you added the rock and after you added the rock is the volume of the rock.
iv) convert this volume measurement to cubic centimeters.

2) Weigh the specimen. Convert this weight to grams.

3) Determine the specific gravity.
Water has a specific gravity of 1, and it weighs 1 g/cc. If your specimen weighs 4 grams and occupies a volume of 1.4 cubic centimeters, then its density in g/cc is 4/1.4 or 2.85 g/cc. Such a rock has a specific gravity of 2.85.

[James Catmur]

Quartz has an SG that is very distinct from diamond, so this is a good test. The nature of the fractures is another good test - chip off a small portion, if the break is flat that tells you a lot about the mineral. Quartz will leave a glass like break while other minerals will have a flat break.