Within the mudstones of Unit
18 are feldspar-phyric basalts. Note the white, euhedral,
early-formed plagioclase feldspar phenocrysts. In the bottom right is
a circular section through an amygdale - an infilled gas bubble.
This is a close-up of the rock
seen in images PAL-03 and PAL-11.
This rather coarse-grained rock is found at the centre of one of the pillows.
- The larger white crystals
are plagioclase feldspar.
- In between them are smaller
crystals of darker minerals, mainly pyroxene.
- What is the evidence for
the order of crystallization of minerals from the magma?
- In general terms, what was
the composition of the magma - acid, intermediate or basic?
Coin is 15mm across
Grid reference: 980
This page is maintained by Roger Suthren
18 November, 2008