Day #12 Deskcrop: The Hague Gneiss

I love the Adirondacks. As a kid my family spent a couple of summer vacations in Saranac Lake and then during my years in scouting summer camp at Floodwood Mountain Reservation hiking and canoeing the High Peaks Region was another highlight. Later, during my undergraduate years at Colgate University I made recreational trips to the Dacks and finally a series of geological field trips, including a couple of weeks on the OC (Colgate’s geology summer field camp). Even now I take every opportunity I can to pass through when vacation travel takes me back east. So it should come as no surprise that I’ll end up featuring quite a number of deskcrops and outcrops from that region. You’ve been warned…

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Hague Gneiss

Today’s deskcrop is one that may be familiar to many geologists, because it is a distinctive metamorphic rock commonly found in collections such as Wards North American Rocks. The rock is the Hague Gneiss, an granulite grade metapelite, also known as a kinzigite. It’s mineralogy reflects its aluminous composition: prominent garnet porphyroblasts are common and readily visible in hand sample and sillimanite (+K feldspar) is commonly found in thin section. The rock is also justifiably famous for its lovely feldspar augen and gneissic fabric – in a structural geology class it might be used as an example of an augen gneiss.

Although it’s a weekday I’m throwing in a bonus outcrop macroGigaPan because, “it would be wrong not to.”

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I’m glad to see even more deskcrops cropping up in the geoblogosphere. Remember you can review all of mine in Google Earth. Join the fun – there’s always room for more!