This is another of the curious and unusual granite types to be found in the western part of the St Austell granite mass.  It is composed of quartz, feldspar and mica just like the biotite granite, but the quartz occurs as curious globular crystals and the mica contains less iron. Over the millions of years since it was formed, various waters, some salty, some hot, some derived from rainfall, have acted on hard granites like this and changed the feldspar to the soft material we call china clay - a process called kaolinisation. Some of the more important china clay pits, such as Littlejohns and Blackpool, are mainly in kaolinised globular quartz granite.   Only about 10-15% of the kaolinised granite is saleable china clay, the rest is sand (mainly quartz) and residue (a fine silty material composed mainly of mica and quartz). 

This granite underwent significant changes in mineralogy during its crystallisation and, under the microscope the unkaolinised granite can be seen to be a complex mixture of early and late formed crystals. It does not contain as much iron as the biotite granite, mainly because colourless and lithium bearing micas tend to take the place of iron-bearing biotite mica. This granite is a suitable granite for the later process of alteration (kaolinisation) to china clay. During the process of kaolinisation iron is released from any iron bearing mica and causes the china clay to be stained red or brown.  For the principle uses of china clay in paper and ceramics, whiteness is a prime requirement, so a parent granite with a low content of iron-bearing biotite mica, such as this one, is the most suitable.  The disposal of waste products from china clay working can present problems, although growing demand for the sand by-product is helping to offset the disposal problem.  In many cases, careful landscaping combined with natural revegetation, has created important new biological habitats, such as lowland heath.  The biological recovery of the landscape of tips and pits, some flooded, promises to be extraordinarily interesting - from where you are standing look around you - this was a site created by 19th century china clay working.