Mineral/rock Identification

[howard_l]

If I might propose a few pointers to anyone seeking a rock or mineral identification. Photos are great but rocks/minerals in my opinion are harder to identify by photo alone then fossils. If before you submit a sample for identification you could do a few simple tests, it would make identification a lot easier.

1) hardness, see if a penny, knife, glass can scratch or be scratched by the sample.

2) See if acid reacts with the sample, HCL (dilute) muriatic acid or vinegar (kids) also try powering a small area if the initial test doesn't work, (dolomite needs this with weak acid).

3) Check for a streak by scratching it on the back of a tile.

4) Try to determine a luster, weather it looks like metal, glassy, earthy, pearly.

5) Cleavage or concoidal fracture.

6) Crystal, this may be hard for beginners but you might be able to tell if it is crystalline or not.

If anyone else can add more please help.

[Bullsnake]

Thanks howard_|.

I recently bought a beginner mineral test kit at a science shop. It had the items mentioned in the post, however, the guy pulled out the penny to look at it and said he was checking the year. He stated that the composition changed in 1982, and recommended using pre '82 pennies.

I searched the change in alloy, and in '82 it was changed from 95% copper/5% zinc to 97.5%/2.5%. Both alloys were used that year also.

Is anyone familiar with this concern, and is it enough to skew the result, considering that it's not the concluding factor?

[howard_l]

In most cases you are just trying to get in the ball park, if you have enough known minerals, the test was designed for the next highest hardness on the mohs scale, so gypsum can scratch talc but talc cannot scratch gypsum. The use of finger nail, penny, knife, glass was a quick easy way to get a rough guess doing field work where access to the right mineral would be hard.

[painshill]

I think all US coins in current circulation have a hardness of almost 3 on the Mohs scale.

I would add to Howard's list:

- Try and give a picture of fresh interior rather than weathered exterior.

- Give the rock a sharp rap with something like the wooden handle of a screwdriver or chisel. Do you you get a 'chunk' or a 'ching' sound?

- Say where you found it and the circumstances of the find (in an old quarry is good; found on the beach is less good; from a pile of rubble by the roadside is less good still!)

Roger

[Roadrunner]

I'd like to see this thread continue! I've had a tough time locating geology forums for amateur mineral/rock identification, and have some rocks now I still can't ID.

Anyone else still interested in keeping this going?

[Bullsnake]

I'd like to see this thread continue! I've had a tough time locating geology forums for amateur mineral/rock identification, and have some rocks now I still can't ID.

Anyone else still interested in keeping this going?

For sure!

Also,be sure to keep us updated on your '1st Mystery' thread when the prof. comes to see it.

[Roadrunner]

For sure!

Also,be sure to keep us updated on your '1st Mystery' thread when the prof. comes to see it.

Will do....I was back to the boulder this week and wrote a "thank you" note to the paleontologist. I told him that I hope he can visit the area in the spring, and will keep bugging him nicely - until he hopefully makes it out here (I didn't tell him that last part). He was planning to do some other studies in the area, and that is when he says he thinks he can come by.

In another area about a mile from the boulder site, I've now found some fairly large sheaves of what I initially thought mica - but the spouse says it is calcite. Some of it is gray, some smaller pieces lemon colored, and some totally transparent. But when I was digging with the rock hammer - the 'stuff kep coming up. It also covered areas of a hillside where in the winter, one would have sworn it was ice. I thought for a while it was broken beer bottles there was so much of it, but it was rock.

I've been scouring rock and minerology identification sites, and will post some pictures in here.....probalby is calcite. I just have to upload the photos now to photobucket.

Edited October 8, 2012 by Roadrunner

[Roadrunner]

I put vinegar on some and got absolutely no reaction, so it isn't calcite after all. I don't know what it is - here is a close-up.

Here are some more....

The same rock above from the back - first further away, then closer up;

BTW, these rocks aren't wet.

When I was digging for a metal hit with my metal detector (more often than not a .45 caliber slug or just a "hot rock") I was digging up what I have in my hand below (wow - I need a manicure);

Edited October 7, 2012 by Roadrunner

[Roadrunner]

Here is some thicker of the stuff from the side;

Another one from the side;

Same as above, different view. You can see I was having trouble with the light - it was getting cloudy.

And one more side view of a different specimen;

Edited October 7, 2012 by Roadrunner

[AgrilusHunter]

It almost looks like mica crystals I've seen before. Yours are different though. I'll be interested to know what others think.

[Roadrunner]

It almost looks like mica crystals I've seen before. Yours are different though. I'll be interested to know what others think.

I've been researching and because it is so soft (it can be scratched with a fingernail), I think it is the variation of gypsum

called Selenite.

[AgrilusHunter]

Selenite does look like a good match. I'm 1 for 3 on mineral identifications on the forum. Looks like its time to crack open some geology text books. Library sales don't fail me now!

[2ynpigo]

Roadrunner is correct. The specimens are gypsum, variety selenite.

[Coco]

I arrive late in the discussion, but I agree with the gypsum.

Coco

[paleostone]

I also added a voice for a gypsum nice and large specimen of gypsum

Edited October 9, 2012 by paleostone

[Roadrunner]

I also added a voice for a gypsum nice and large specimen of gypsum

Thanks.

I'm going to go back there soon. Every time I put a rock hammer in the earth, the more transparent gypsum came up.

On the net, I've seen blocks of the the 'stuff 1500 pounds.

Edited October 14, 2012 by Roadrunner

[Bugz000]

Accidental Hijack!

Edited January 16, 2013 by Bugz000

[Coco]

At first, you should have opened your own subject instead of writing in a other one already existing, because you have your own minerals to be identified, and it would avoid the difficulties of answer..

Then, your pics don't have to exceed 2 Mo (Mb) to be put on this forum, and it is very sufficient to see what there is to see above if they are good quality (enlightened, clear etc...).

It is better to make an effort (ask help if necessary) to put your photos directly on the forum that on a site where it is necessary to click "X" time to see something, and finally be able to help you.

All the best.

Coco

[Bugz000]

At first, you should have opened your own subject instead of writing in a other one already existing, because you have your own minerals to be identified, and it would avoid the difficulties of answer..

Then, your pics don't have to exceed 2 Mo (Mb) to be put on this forum, and it is very sufficient to see what there is to see above if they are good quality (enlightened, clear etc...).

It is better to make an effort (ask help if necessary) to put your photos directly on the forum that on a site where it is necessary to click "X" time to see something, and finally be able to help you.

All the best.

Coco

thanks for the heads up i'll go make a new post- i assumed this was like a universal "id" thread, i do apologise

edit: - new post is up, thanks again

EDIT: Link to new topic: >LINK<

Edited January 16, 2013 by Auspex

[Coco]

Coco