Dolerite

Better grade intervals are typically associated with quartz veins, while low-to-modest gold grades are associated with alteration zones around quartz veinlets, veins and shears in the dolerite host rock in wider intervals.

GJRC028 intersected black shale and silicified dolerite with sulphide mineralisation and quartz stringers but was terminated at 130m due to difficult drilling conditions associated with running sands in the overlying Gidji Paleochannel.

In the southern midlands as far south as Hobart, the dolerite is underlaid by sandstone and similar sedimentary stones.

Much of the island is composed of Jurassic dolerite intrusions (upwellings of magma ) through other rock types, sometimes forming large columnar joints.

Tasmania has the world's largest areas of dolerite, with many distinctive mountains and cliffs formed from this rock type.