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Canadian Gneiss from New York State

Submit an Entry: My Metamorphic Rock

By Virginia Peterson

Canadian Gneiss from New York State

Gneisses

Where This Rock Is From (place, type of locality, etc.)

These rocks are from the southern shore of Lake Ontario, somewhere near Oswego, N.Y., but originating in Canada. As I remember, this was a beach made entirely of rocks of this size or larger, hardly any sand, with a great variety of types to choose from.

What This Rock Is

The one on the right is a gneiss. The one on the left doesn't have as much directionality in the crystals, but has an "augen" or "eye" visible, as well as a vein where it was later cracked. The minerals surrounding the crack have been altered in color.

What I Like About This Rock

These rocks are very smooth and rounded, nice to hold in the hand. I coated both of them with clear nail polish to help bring out the colors.                                                                            .

Advice

  • I've started collecting large glass jars to display rocks like these in, it keeps them from getting dusty. ("rock candy")

Andrew Alden, About.com Geology, says:

The one on the right is a classic augen gneiss. These are generally thought to represent large grains of equigranular minerals (usually quartz) that were only partially "processed" into the typical gneissose texture that the rest of the rock displays. Nail polish works well on a rock like this, especially because it can be completely removed if need be.
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