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PhotosIs this photo of massive Epidote?

21st Oct 2019 23:37 UTCJonelle DeFelice

Can anyone possibly confirm this very green section of Blueberry Hill quarry wall is massive epidote?  It is thick in spots, thin in others, shiny and rather smooth... and NO I cannot do a pin test as I don't have the wall with me right now...


22nd Oct 2019 00:18 UTCThomas Lühr Expert

Hello Jonelle

It does rather not look like epidote to me - one should see some structure even in massive epidote, but this looks to me collomorpous or at least very fine-grained. 
And yes, a rough hardness test would be quite helpful ;)
Nontronite (or maybe an other clay mineral), some kind of silica (opal, chalcedony), allophane, a serpentine group mineral come ad hoc in my mind ...


22nd Oct 2019 01:23 UTCPeter Cristofono

Hi Jonelle,

It's epidote. The "polished" epidote on the wall is the surface of a slickenside, formed along a fault. The rocks on each side of the fault slipped past each other, causing the smooth surface.  Slickensides are fairly common in that part of Massachusetts.
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