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Geology/What's this rock?

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Expert: Fraser Hamilton - 10/18/2009


Question

Glass Rock
Hi. I live in Minnesota. While taking a walk in the woods we noticed this rock, in attached image. It looked like a chunk of dirty ice. It was shiny just as though it was wet, but after bringing it inside for a while we noticed it stayed this way. It looks like it is glass mixed with brown rock. The brown rock on the surface is reletively soft and crumbly but the underneath pretty hard. The rock itself is about 8" in diameter. The other odd thing about it is it was sitting on top of the soft ground there, not into it really. This is a very remote location so I'm sure nobody just put it there. Did this fall from the sky? Could it be some sort of meteorite? Thanks Tom

Answer
Tom:
First my apologies in taking so long to get back to you.  You certainly have an interesting rock and good observation skills.  My first guess is that it is a piece of quartz. If that is what it is, it would likely either be a piece of glacial drift or a something that has worked its way to the surface over a very long time.  It could easily get moved to the surface through frost action (in the winter obviosuly).  The soft crumbly stuff is probably just "mud" that makes me think that is glacial drift (soemthing dumped by the glacier many 1000s of years ago) and the soft stuff is just that, mud.  Of course there is always the possibility that it is the remains of a shooting star, asteroid, etc.  You might consider contacting the geology dept of a nearby University and asking to speak to a petrology professor or grad student.  They could probably help you better.

Good luck.

I would be interested to hear what else you learn.

Regards

Fraser Hamilton

Expertise

I have over 15 years of professional experience in the environmental geology field. I am well versed in general geology types of questions and answers. In addition I have a keen understanding of physical stratigraphy (especially in the Valley and Ridge of Central PA) and cycles.

Experience

Eight years of education, fifteen years of professional experience. Have worked or studied in ME, PA, TX, KY, IN, TN, OH, WA and Scotland.

Publications
Geological Society of America
American Association of Petroleum Geologists
Properties Magazine
Cleveland Bar Association
Cleveland Engineering Society

Education/Credentials
BA Geology/Math, University of Maine at Farmington
MA Geology - Physical Stratigraphy, Temple University
Post Grad Studies Geology - Texas A&M University

Awards and Honors
Distinguished graduate teaching award, Temple University

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