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Shiny Rocks
Shiny Rocks  
Hello!  I found some very interesting rocks in the river by my home today and wondered if you might be able to shed some light as to what type of rock they are.  The rock in the attached picture is very heavy and full of a shiny, champagne, white-gold-like mineral/material that is very reflective almost like the inside of a shiny insides of some shells.  When I pulled a piece of the mineral/material off the rock, it comes off as a chunk then quickly splits into different layers (each the same in size and shape) and paper thin.  The mineral is almost transparent like glass but is very smooth and papery-like in texture.  Extremely reflective.  Please let me know what type of rock it is and/or what the material is inside it.  This material is also in different rocks (not of the same kind) and in this mucky, muddy-like sand from the bottom of the river.  There was also lots of it trickling through the water in little pieces.  Thanks!

Hi Megan,
Looks like you have a piece of mica.  That's a mineral made up of different elements combined with silica and oxygen.  It has perfect cleavage which means it can split into thinner and thinner pieces. They can get so thin you can see through them.  In fact, sheets of mica were placed in the doors of furnaces to view the fires inside.  From the color of your specimen, it looks like you have a variety of mica called muscovite.

This site will give you a little more information:

The next sites display some images of mica:  peices

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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