194 THE MINERALS OF NEW SOUTH WALES. 



Commonly met with as an efflorescence in caves and under 

 sheltered ledges of the coal measure sandstone, as at Dabee, 

 Walierawang, Mudgee Road, the mouth of the Shoalhaven River, 

 and other places where it is usually associated with epsomite. 

 Also found in the crevices of a blue slate at Alum Creek, and at 

 the Gibraltar Rock, Shoalhaven. Occurs as a deposit with various 

 other salts from the vents at Mount "Wingen, together with native 

 sulphur in small quantities. 



Websterite. 



Chem. Comp. : Aluminium sulphate. Reported to occur on 

 Brush Creek, Dumaresq River. 



Silica. 



Quartz. — Rock crystal. 



Chem. comp. : Silica. Hexagonal system. Found in nearly all 

 parts of the Colony, and in crystals more or less perfectly developed ; 

 the most common form is the prism combined with the pyramid. 

 Occasionally prisms closed at both ends by planes of the pyramid ; 

 also double pyramids. Such crystals are, however,- usually small 

 and generally occur in quartz porphyries, or are derived from the 

 decomposition of such. 



Occasionally some very large crystals are met with, notably at 

 Newstead Tin Mine, New England, where, in one of the shafts, 

 crystals nearly one cwt. were met with ; within these, crystals of 

 tinstone were often found disseminated. 



Large crystals of smoky quartz are common almost throughout 

 New England, as at Bingera, Inverell, Cope's Creek, Uralla, and 

 at Mudgee. Some of the rock crystals found in the alluvial tin 

 deposits present a very pretty appearance, from the presence of 

 numerous minute fissures and internal films, streaks and patches 

 of yellow, orange, and red colours. Most of the crystals from 

 New England have one face of the pyramid much more largely 

 developed, so much so in some cases as to almost obliterate the 

 others. 



Elongated pyramids containing disseminated crystal of cassiterite 

 are common at the Albion Tin Mine ; these crystals of quartz are 

 dull and slightly rough on three of the faces, and bright on the 

 opposite three. 



Smoky brown Cairngorum and limpid quartz crystals are plentiful 

 in Ranger's Valley, River Severn ; Macintyre River, Middle Creek, 

 Byron's Plains. 



Quartz crystals with rounded edges and dull surfaces, as if 

 acted upon by hydrofluoric acid, occur in the coarse-grained granite 

 on Mann's River. 



