AboutC. Robert Reszka, Jr. Expertise 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.
Experience I have been working for the State of Michigan for 24 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.
Organizations Michigan Basin Geological Society
Publications Decade of North American Geology.
Bedrock Geology of Michigan
I teach in a Native Village in the North Slope of Alaska. Recently, a mom brought in this large sample and asked me to help identify it. So, here goes: the sample is large, oblong about 27 cm long, 14cm high and 14 cm wide. Very light gray with a porous composition. It is very lite for its size, a little over 5 pounds. Crusty and flaky, easy to crack, easy to flake off. The mom found it on the beach in Arctic waters. Thanks for any help.
Answer Hi "E",
This is very interesting. When I read your question I hadn't seen the photo yet but it sounded very like a specimen of pumice. I have since seen the picture you took and I am virtually certain of it now. The most definite characteristic of pumice is that it floats. Some pieces bob around like a bar of soap while others don't do so well.
"Pumice" is derived from Latin, pumex, which means "frothy". That's because it has that look, usually. It's really a glass and not a rock and is classified as volcanic. It comes from a melt that is rich in water and volatiles (gases and such). As the magma (melted rock) approaches the surface of a volcano, the volatiles, in this case, all escape leaving tiny holes and passages within the rock giving it a frothy appearance. When it reaches the surface it cools very rapidly so you get a rock that's full of empty spaces. All those holes are the reason most of the rocks can float; there is just so much empty space that it will displace a lot more water than it's size would suggest. However, it will get waterlogged and sink after a time.
It's used in concrete and cement, landscaping, soaps and toothpaste, among other things.
You can find it all over the World, including North America; Arizona, New Mexico, California, and Oregon.
How it got to your shores in Alaska......your guess is as good as mine. But I would suggest it might have been in the middle of freighter transport, in rough form, to a plant for manufacture of cement or concrete (or something else) and maybe there was a wreck. Since it floats it could have floated for a long time. Also, we can't discount the possibility of deposits of pumice in that region of the Earth. It's at the subduction zone of the Aleutians island arc, which means a lot of volcanism. It's NO stretch to assume the production of some pumice in the very active volcanoes of Alaska and the west coast.
Here's a pretty good site on pumice. You might want to check it out to get some more information on it:
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