Elvan Dyke / Rhyolite - Praa Sands - 2 (S16)

At the western end of Praa Sands in Sydney Cove is an exposure (20m wide strip) of red brown Rhyolite (Elvan) , a quartz-feldspar-porphyry.
Intruded as a magma (molten rock) through a vertical crack in the earths crust 270 million years ago , the very viscous magma crystallised as Rhyolite with Feldspar phenocrysts (crystals).
The Crystals exhibit a well developed - similar orientation (Flow Texture).
The surrounding rocks are dark Mudstones .
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Location - Praa Sands is between St Michael's Mount and Porthleven - section 16
Ref:
188C
Date:
2014-09-21 00:00:00.0
Location:
SW 573 280
Photographer:

Elvan Dyke / Rhyolite - Praa Sands - 2 (S16)

At the western end of Praa Sands in Sydney Cove is an exposure (20m wide strip) of red brown Rhyolite (Elvan) , a quartz-feldspar-porphyry.
Intruded as a magma (molten rock) through a vertical crack in the earths crust 270 million years ago , the very viscous magma crystallised as Rhyolite with Feldspar phenocrysts (crystals).
The Crystals exhibit a well developed - similar orientation (Flow Texture).
The surrounding rocks are dark Mudstones .
---------------
Location - Praa Sands is between St Michael's Mount and Porthleven - section 16
Ref:
188C
Date:
2014-09-21 00:00:00.0
Location:
SW 573 280
Photographer: