Thursday, February 11, 2016

Mind your Minerals

     Remember the last time somebody said to you, "You're a real gem"? Well, me neither. But, just in case such a compliment comes our way (and it should!), here's the definition. A gem is any mineral prized for its beauty and rarity, usually enhanced by cutting and polishing. Of course, this begs the question, "What's a mineral?" And the answer is: a naturally occurring solid with a specific chemical composition and a distinctive internal crystal structure. This structure is controlled at the atomic level by a particular, repeating three-dimensional pattern and seen externally as flat faces arranged in geometric forms.
     Now that I've got you thoroughly confused I'd like to recommend a trip to this weekends Gem, Mineral and Fossil Show and Sale  at the New York State Museum in Albany. There you'll see displays of both natural and faceted minerals in shapes and colors that astound. Plus, you can talk to people who really know what crystals, minerals and gems are. Let's not forget about fossils. There'll be lots of those as well. Admission is five dollars with specimens for sale from down to earth to the sky's the limit.

     Leave enough time to tour the museum where there's an amazing display of New York State minerals along with other exhibits on geology and a host of natural, historical and cultural aspects of the Empire State.
     Unfortunately, Washington County seems to be the Rodney Dangerfield of the neighborhood when it comes to minerals. So little respect that I remember only one measly item from here in the museum's huge collection. And that lone piece wasn't particularly impressive. It's St. Lawrence County that gets most of the glory but Essex, Warren and even Saratoga Counties seem to have a richer bounty.

     Given that I don't know much about minerals and Washington County isn't over-endowed, I should probably sit down and shut up. But what fun would that be, so here are a few suggestions. You can see garnets embedded in the gneisses of the Lake George mountains. Most are small but they're still fun to find. Pegmatites are fairly common and sometimes yield nice specimens. These are course grained intrusions that can be found in veins cutting thru bedrock. They originate from magma with a fair amount of water in it. As the fluids cool, crystals sometimes grow. There is a striking pink pegmatite in a road cut along Rt. 22 in Dresden. It diagonals up the face from ground level and is easy to examine. These type of rocks were also quarried (over a hundred years ago) off of West Road in Fort Ann. The feldspars and quartz's mined here were used in pottery making.

     Graphite used to be mined on the west side of South Bay and magnetite in Fort Ann up by Lake Nebo. There may be other minerals associated with these digs. There are also reports of gravels cemented with calcite crystals from pits in Putnam. The problem is that all of these sites are private and posted.
     Further east in the Taconics, phyllite and slates are  found and they sometimes contain veins of quartz and "ringer" inclusions. You might also find porphyroblasts with crystals of various minerals. Even the shales of the Hudson/Champlain lowlands can surprise. In my farm shale pit I've broke out small cavities with nice quartz crystals growing inside.

     Fossils will be located mostly in the limestones between the Taconics and Adirondacks. I've seen stromatilites, snails and bivalve shells. Better to just look at these and leave them in place for others to enjoy. I know that plain old rocks (a naturally occurring and coherent aggregate of one or more minerals) aren't as sexy as crystals and fossils but Washington County has a nice variety and in collecting these you'll learn about the regions fascinating geologic history. As the saying goes, "The Lord must love common people because he made so many of them." And common rocks, I might add.

Digging Deeper
     - Capital District Mineral Club
     - Burlington Gem and Mineral Club

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