A distinct feature of the world-class Mount Isa copper
system is the presence of 
a massive silica body enveloping the chalcopyrite ore body
in the Urquhart 
shale. Because silicification may be genetically linked to
the copper 
mineralization, it is important to understand its formation.
It can be shown by 
numerical simulations of reactive transport processes that
both hydraulic head 
and buoyancy driven flow are capable of generating
silicification patterns similar 
to the field example. Considering the physical conditions
required to form the 
observed patterns we suggest, however, that head-driven flow
rather than 
free thermal convection produced the silica body. Free
convection requires very 
special conditions and only one of several possible
scenarios reproduces the 
observed silicification whereas any of the tested forced
flux scenario is capable 
of doing so.

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