|
Thin
sections of “Cold Moor Ironstone”. |
Sample taken from trial adit on west side of Cold Moor. |
|
|
|
|
|
|
|
Top two photo’s are in plane polarised light (PPL). and
cross polarised light (XPL).They show bioclastic debris within a matrix of siderite
with a dark patch in the upper part
showing part of a phosphatic nodule
interestingly enclosing two
chamosite? ooliths. The characteristic
concentric structure of the ooliths is
visible in XPL as well as the extinction cross. (For scale the lower oolith
is ~1mm width, left to right.) |
Bottom two photo’s are from a different part of the thin
section. The rock is dominated by bioclastic debris within a matrix of
siderite. Scattered quartz grains are visible, showing grey interference
colours. According to this thin section the rock would be described as a
bioclastic ironstone with phosphatic nodules. The bioclasts have been
interpreted as echinoderm and coral debris. The sample was taken from the
trial adit on the west side of Cold Moor (about NZ550 032) |
