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Found this in my yard

So as I was digging in my side yard I’ve found a lot of rocks. For relevance, I live in Wisconsin Rapids, WI and about a block from the Wisconsin River. (I’m just about in the center of the state) So needless to say my yard is mostly sand and rocks. (Especially my back yard) about 2-4 inches under the top soil is a huge layer of all sizes of rocks. So when I was augering my fence post holes and scooping out the dirt I found this guy. And here he is all cleaned up. There is some of the yellowish color but not as overall as some of the photos show. Not sure what the yellowish is. Any help would would be appreciated and I’ll be posting more unknowns soon. Thanks

Looks like Quartz. But would need to do some testing. Do you have any gem testing equipment?

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Just a standard science kit for streak test and such.

Yeah quartz. The angles are 120 degrees, and some horizontal striations parallel to the base.

Any ideas as to the yellowish coloring?

Probably goethite or an other iron oxide or hydroxide.

You talked about tests?

Maybe you could help with this?


I also have a green I can’t seem to figure out

A specific gravity tester compares the weight of your stone in air to the weight of your stone in water. This is on amazon Kit, Universal Specific Gravity for an Electronic Scale I believe you have to buy the gem scale separately. After you test the Specific gravity you google the results and there is a list of stones and gems and their specific gravities listed in order.

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So how would I use that when there’s multiple minerals and such?

You would get the specific gravity and a list of possible stones that it could be, lets say 6 possibilities, than you would google each one and see if any looks like your stone.

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So specific gravity would be the best way to identify my stones and rocks?

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If you have a nice polished surface like a gemstone , a refractometer would be a useful tool. But it looks like you have mostly stones so I would choose Specific gravity to get you in the range of possibilities. A magnet can also be helpful as some stones contain iron. But I think specific gravity would be your best bet to narrow the field and google for a photo.

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Google has not been my friend in helping identifying anything so far lol

No, not when the stones/rocks consist of multiple minerals. Spec gravity works best with single crystals, but can be very error prone the first time you use it. Your other stones look like quartz in a matrix, no gemquality material, and i am a gemmologist, not a mineralogist.

It looks like very light weight and powdery material, so probably volcanic tuff.

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It’s actually quite heavy and not powdery

Then it is not vulcanic tuff :joy:

I would try a uv light. If it is corundum it will glow red. Otherwise I would try to chip a small piece off and do an RI and/or SG.

The shortwave there is only one spot that glows a different color and it’s a light yellow but the picture doesn’t show the color the best and some of the color on long wave turns pink 20210628_131229|375x500

A Quartz for sure…