Geoscience Reference
In-Depth Information
338
339
338
Historic clay brick from the Great Wall of China,
comprising particles of quartz (white/grey), feldspar
(grey), mica (brown), and granite (large particle) in a
matrix of fired clay (black); XPT, ×100.
339
Close view of historic clay brick from the Great
Wall of China, showing particles of quartz and
feldspar (white) and mica (dark brown) in a fired clay
matrix (light brown); PPT, ×100.
340
341
340
Same view as
339
in cross-polarized light. The
fired clay matrix now appears black; XPT, ×100.
341
Historic clay brick comprising particles of quartz
(white) and flint, with a matrix of fired clay (dark
brown). Flint particles exhibit evidence of heating
with one exhibiting red discolouration (upper left) and
another appearing calcined (lower right); PPT, ×35.
342
343
342
Same view as
341
in cross-polarized light. The
fired clay matrix now appears red; XPT, ×35.
343
Close view of historic clay brick showing
particles of quartz (grey/white) and flint (centre left)
with a fired clay matrix (red); XPT, ×150.