JASPER ???

[CaptEsteban]

Found in Tenn. valley. Is this Jasper. I can see where flakes have been taken from it.

 

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[stdenis_jd]

Is say it's flint, basically the same thing as chert and very similar to jasper

 

[DDancer]

I'll call it jasper as flint tends to be black and grey in appearance. Both have similar hardness and can be knapped into tools and both have similar chemical make ups. There is a debate on what constitutes chert and chalcedony minerals : https://www.mindat.org/mesg-7-245968.html

I go by coloration and luster for my opinion on your specimen. Flints, chert, tend to have a more mat appearance than chalcedony minerals.

 

[stdenis_jd]

Thanks for the mindat link DD - it's always a bit of a debate no matter where you go, over chert vs. flint vs. jasper....

In Michigan we have quite a lot of all of those - I would say myself and other rock hounds take a pretty general approach for our area...

Jaspers are generally variations of red to black and often red with black stripes due to the high amounts of iron and hematite banding in our local geology, and they are usually like you said more shiny and waxy lustered.

We usually call similar structure and hardness, but with white/gray through gray all the way up to black, also with variable luster (sometimes matte, sometimes waxy) "cherts"

Usually we call yellow to brown cherts "flint" for the most part. So I suppose in this instance your ID as a jasper would be more accurate even by my own description

That link was especially helpful with the blocky microcrystalline vs fibrous microcrystalline structure descriptions, that will help quite a bit

 

[DDancer]

Glad you found the link useful stdenis. Came across it a while back during a head scratch on classification for jaspers. Turns out many of the lay classifications for minerals in the microcrystaline silicates are dependant on coloration and luster. Tomatoe's vs Tamatoes These minerals are such a mixed bag its often just up to the collector to make up their mind what to call them. With only a photo I can only call it as I see it