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What kind of green stone is this?


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Gabbro is my guess.

It's like basalt lava, except it forms underground, like granite,

Pennsylvania, right?

Homework for you:

http://www.dgs.udel.edu/sites/dgs.udel.edu/files/publications/ri59.pdf

http://mrdata.usgs.gov/geology/state/fips-unit.php?code=f42095

Edited by weaver hillbille
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Not knowing where exactly the sample came from, I would guess it is a "Greenschist", that is, a metamorphic basalt from the precambrian period. The sample looks very similar to "Greenschists" of Virginia's northern Mts.

What is the rocks hardness?

Here is a link to the Geologic Map of Penns: http://www.dcnr.state.pa.us/topogeo/publications/pgspub/map/index.htm

This can help you pin down the types of rocks found in the area you are collecting in.

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Gabbro is my guess.

It's like basalt lava, except it forms underground, like granite,

Pennsylvania, right?

Homework for you:

http://www.dgs.udel.edu/sites/dgs.udel.edu/files/publications/ri59.pdf

http://mrdata.usgs.gov/geology/state/fips-unit.php?code=f42095

I would lean toward Serpentine due to all the green (olivine?) in it. That is why I asked about the hardness. Serpentines are relatively soft, around 2.5 to 5. Most of the igneous rocks of Penns have been metamorphosed.

Gabbros tend to have low (< 30%) olivine (green color mineral) content. This hand sample has a lot of a green colored mineral (70 - 80 %) which would make it a Peridotite, that is, if the green mineral is olivine.

A'nt Petrology a hoot. :ROFL:

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I reserve my right to change my answer to Peridotite :4chsmu1:

http://www.geol.umd.edu/~piccoli/100/ch4.htm

http://www.geol.umd.edu/~piccoli/100/Image8.gif

Edited by weaver hillbille
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