I have recently finished tumble-polishing some of the stones I collected from Gemstone Beach during my “Southern Sojourn” at the start of this year. This month, I will post one of these stones each day. Gemstone Beach is on the coast of Te Waewae Bay in Southland.
I chose Stone of the Day #1 from the top of a plateful that had finished tumble-polishing last week. It is a small flat stone, 3.25 cm at its longest, 2.5 cm wide, and about 0.4 cm thick. Its mottled appearance and bright green crystals caught my eye.
I am not sure of the identification of the stone, though I suspect it is metamorphic. The bright green crystals, and the lighter green spots, are probably epidote. Epidote is a common pistachio-green silicate mineral. There appear to be some tiny hollows lined with bright green crystals but the surface of the stone is actually smooth – there must be something like transparent silica filling the hollows.
Sandatlas has an excellent introduction to epidote, and “A Photographic Guide to Rocks and Minerals of New Zealand” (2011) by Nick Mortimer, Hamish Campbell and Margaret Low has an entry on it (see below).
This is typical of the kind of stone I look for on Gemstone Beach – it has intricate and colourful details that fascinate, that only become clear upon close observation.
Go to Stone of the Day #2. Go to the Series Index.