Michigan Septarian Nodules (Geodes) “Lightening Stones”

Crystal, Geology, lake michigan, michigan, Minerals, rock hounding, Septarian, U.P.

Lets start with the second most identifiable stone for Michigan: “Lightening Stones”. They are referred to this name by local ‘Michiganers’ and actually are variation of a Septarian Nodule. These Michigan Septarians were balls of clay that formed on the ocean floor somewhere around 50 million years ago, over time the balls of clay developed cracks that were later filled with yellow-White Calcite. They are considered what is known as a ‘Pseudo Fossil’. Occasionally you will find them with Crinoidea Fossils or with ‘Fossil Graveyard’ markings. I am unsure of the reason they refer them to Geodes, they do have a calcite filling but are not hollow on the inside and only go as deep as the original crack in the clay. I have attempted a different ways to polish these, it has taken awhile with trial and error. I have tried sanding down with different pieces of a drummel and even just trying to polish with a felt tip on a drummel. When they are under a drummel the clay starts to turn dark almost black and you will have the biggest clay dust storm. I have tumbled a few of these guys and they do come out very nice and smooth but they do turn a very dark brown, the calcite turns a little gray, and they do not shine, but the end result is they are usually smooth. I have also noticed that you can buy a very light craft finishing spray and if you take your time and make very light coats you can make them super shiny with a smooth outer appearance. With the polishing spray you have to be very careful, I have ruined quite a few from either coating one area too much and having half of it polished with less polished spots. Also make sure you are on a completely flat surface with no textures because it will imbed in the spray. I accidentally put the little nodules on a paper towel to dry, Lets just say they now have a nice floral paper towel impression! Ha! These special little guys are only found in the Allegan County Area of Michigan. They are said to be mainly found in South Haven ( I would suggest what is called ‘Deer Lick Creek’) Or in the Holland Area (Most people refer to ‘Pier Cove’). I have some photos of the current ones that I have: Picture One are some simple pendants made from a few tiny ones. Picture two contains the ones I found on my last trip only after hours. Picture 3 has a box of ones I have found in the past month. Picture 4 is just a fun example of how I present them to sell. Picture 4 is one of the largest ones I have found. They are primarily a little less the size of your palm, but on occasion you can find ones that large or even as tiny to make some pendants or charms.

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