ON SOME NEW SOUTH WALES MINERALS. 47 
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but of a more compact character. Others consist of soft friable 
pyrites with the fissures filled in with hard white quartz, thus 
forming septa. s the rock weathers and exposes the concretions, 
the granular pyrites falls out and the septa are left in the form of 
irregular, exaggerated honey-comb structures (fig. 
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rom solution, not 
in the form of cubical crystals, but in the form 
nodules of marcassite, 7.¢., the rhombic and less durable 
form of iron pyrites. 
fissures would necessarily form within, since the hard 
outer portions would not give way so readily as the 
softer and weaker inner portions. 
