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My great grand mother gave me jewels and rocks from around the 1920s or 30s. She lived I the Milwaukee area. They are extremely shiny,metallic, crystal like and silver... There it's also a clear one I the picture is like too know about. If i take the silver rocks and scratch granite it leaves a scratch but then if i barley drop it tiny pieces break off...most are perfect silver some i noticed have white developing. There's no need for a light to make these shine. Please help id like to make a necklace out of line she just passed last night m thank you.

Hi Kristina,
I was thinking you specimens might be pyrite or marcasite but your description of a silver color and the pictures makes me pretty certain you have metallic slag.  That's the waste product left over after the smelting process.  Itís the undesired impurities in the metals, which float to the top during the smelting process.  The metals start to oxidize as they are smelted, and slag forms a crust of oxides on the top of the metal being smelted. When the smelting is completed, the slag is skimmed from the top of the mix and disposed of.

Slag can be glassy or metallic, dull or shiny, silvery or gray to black.  It all depends on what the original ore was and what kind of smelting process was used. Slag is commonly composed of oxides of silicon, aluminum, magnesium, and sulfur.  Depending on the type of smelting process, it may also contain phosphorous, calcium, and ash.  These can be remnants of flux materials, such as limestone used in the process, or chemical reactions between the metal and the furnace lining.

Your specimens look like a metallic silicate slag.  I have seen many examples from all over the United States.  It is very useful and can be found in road and train track ballast, brick and mortar, cement, glass,phosphate fertilizer, or even jewelry (so go ahead and create some bling).

I have been unable to find many images on the Net that display specimens like yours to good advantage but if you navigate to these sites you'll see an image that looks much like your samples:  MAY STILL BE ACTIVE  THIS MAY STILL BE ACTIVE
Hope this helps.


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C. Robert Reszka, Jr.


I can answer any general geology question (rocks, minerals, stratigraphy, geomorphology etc.). My expertise is in the geology of the Michigan Basin, PreCambrian, Paleozoic and Recent. I can answer questions concerning mining and petroleum exploration and production and the laws concerning those activities. I can also answer questions concerning stratigraphy of the Michigan Basin. I will also answer questions about mineral and rock collecting in the Basin. I won`t be able to answer many specific questions on hydrology, geophysics or geochemistry. I may be able to answer very general questions in those venues.


I have been working for the State of Michigan for 36 years as a Geologist and a Resource Analyst. I have experience with Subsurface Geology and Petroleum Geology, mining in Michigan, and Sand Dune Mining and Protection issues.

Michigan Basin Geological Society

Decade of North American Geology.
Bedrock Geology of Michigan

BS Wayne State University

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