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
Question We have a cottage in the tip of the thumb of Michigan on Lake Huron - sunrise side. There are LOTS of rocks on our beach front...is it likely I could find geodes? If so how does one identify them before breaking them open to discover the crystal formations inside. I would love to start exploring rocks with my grandsons...Thanks, Vickie
Answer Hi Vickie,
The short answer is, I would not expect to find geodes on your beach. Although they can be found in Michigan, they are not common; as they are in Keokuk (Iowa), Ohio, or Indiana. Some have been found in Houghton County and some in Arenac. There is also a type of rock called "ironstone", which is considered a geode, found near Holland. I know of no area where geodes are found near you.
However, rivers and streams move rocks. So does the movement of Lake waters. So I would not say that it is impossible to find geodes on your beach. Just highly unlikely.
As to how to identify them...there are a couple of ways. We all have an idea of how heavy something is before we pick it up. It is just intuitive. Gold will feel heavier than it would look when you picked it up. You would notice. Just pick up the rock; if it feels lighter than you think it should you might have a geode. Remember most are hollow so all that "middle" rock is missing.
Another way is to tap it with a hammer. It will sound hollow. It will not ring like a solid rock will.
There is another way, but it is specific to a type of geode; one we call a "floater". A floater is filled with, I think the technical term is "gazillion", minute doubly terminated crystals that are not attached to the wall of the cavity. If you have one of these, shake it. You will hear the rustle of the crystals inside the geode.
As I say, not likely. But don't let that stop you from looking for a geode. You can never be sure. Also, there are loads of rocks out there that are worth collecting on there own merits. Have fun!
