The magazine editors received a message recently from a reader, Edward, with a question about this very unusual stone sphere. Here is the message:
“I have attached a photo of what I think is a paleoindian (?) marble. Found along the South Platte River in Littleton, Colorado, it is made of coarse-grained quartzite with the grains less resistant to erosion than the silica matrix (i.e., the grains are slightly recessed relative to the matrix cement). I positioned the marble to show 2 specs of what appears to be a vermillion coating (red ochre?, cinnabar?) in the middle of the marble. Numerous specs of this material appear on the ball, and are preferentially preserved in the grain recesses.
Any thoughts? Would it be worth trying to analyze the vermillion material (perhaps latex paint according to a friend)?”
We have given Edward some of our preliminary ideas. Can you help? Has anyone seen a marble like this? Anyone else found or own a marble like this? Can someone identify the type of quartzite crystals on the surface and/or the matrix? Because of the crystals we think it must have been made by grinding; any other ideas on how it was made?
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