Muscovite - Animal? Vegetable? Mineral?

When I was a kid, like a lot of others, I collected rocks, mostly ones with fossils of sea shells. Half a century later I am looking at rocks again, driven by an interest in the geography and geology of the places where I hike. In an earlier post I documented my quest for garnet schist. Then in September, while hiking around the Dorsey tunnel on an eroded section of the trail, I came upon a few small rocks with a strange feature. They had what looked and felt like sheets of transparent plastic in them. I guessed they must be some kind of mica, but I had never seen anything like it before. Then last week my brother Chris, knowing of my renewed interest in rocks, handed me a small book, Rocks and Minerals, published in 1957 by Golden Press. There on page 97 was a perfectly drawn illustration almost identical to one of the rocks I had picked up. It was Muscovite, a type of mica as I had suspected. Here is a photo of my rocks, with a dime provided for scale and a knife blade to demonstrate the plastic sheet-like quality of the mineral.

Geologizing

The Prospector's Dilema

The second leg of this morning's hike in Leakin Park, the leg south of Windsor Mill Road on the east side of the Gwynn's Falls was a prospecting expedition. I was looking for an outcrop of schist rock studded with garnets, which I heard about at a presentation I attended a few weeks ago. My mission was an epic geological fail. Ok, not epic. I found outcrops, but did not see or recognize any garnets, I am not even sure if the outcrops were schist or some other kind of rock, such as gneiss or granite or a combination of the three. So, like many prospectors before me, I know that there are garnets (undoubtedly industrial grade, so don't get all excited) in them thar hills, but I could not find them. Or worse, I found them, but did not recognized them. This calls for a return trip with my rock guru, Ira, preferably in the late fall, when the leaves are off the trees and vines that cover a lot of the rocks. My experience is that when looking for structures (natural or man made) in a forest, I am more likely to find them in winter when the trees and vines are bare. There are more photos of the rocks I saw here.

p.s. Unpon review of the photos, Ira said I was in the schist, but agreed that closer inspection should wait until the end of fall when the rocks are clear of leaves.