328 T. G. TAYLOR AND D. MAWSON. 
grained rocks, only approximate. Under the head ‘‘ Order 
of Consolidation,’’ small tables are given showing approxim- 
ately the relative age and duration of the mineral con- 
solidation. Ordinates may be taken to represent starting 
points, while abscissse indicate periods during which 
crystallisation went on. 
No. 1. Locality Loveridge’s Quarry, Bowral. 
(See Plate 26, fig. 1.) 
Texture—Hypidiomorphic granular. 
Fabric—No base is present. The rock is composed almost 
wholly of a mass of orthoclase with some grains of 
ilmenite and a fair amount of indefinite dark coloured 
decomposition products. 
Minerals present (in order of decreasing abundance)— 
Orthoclase = at a bis a Bat 
Decomposed ferromagnesian minerals we A0% 
Magnetite and ilmenite ) 
Apatite ' accessory vos, nd eae 
Fluorspar ) 
Calcite and chalecedony—secondary. 
Orthoclase occurs as sub-angular crystals, some of square 
or rectangular shape. Although some few of the felspars 
are clear and transparent, yet the majority are kaolinised. 
Some are converted wholly into a grey powdery mass, 
while others show included parallel rows of brownish 
coloured matter. The latter arrangement is due to the 
fact that cleavage planes offer the easiest point of decom- 
position. Many of the prisms show clear borders while 
the remainder of the crystal is more or less kaolinised. 
Twinning is fairly common, after the Carlsbad law. 
In some sections irregular patches of secondary iron 
oxide occur. They have a somewhat fibrous structure and 
are perhaps due to decomposition of hornblende or other 
ferromagnesian mineral. 
t 4 
Pow ey! z 
