BY.EDWD. B. LINDON, A.R.S.M. 65 
Opat—Comp. Si O, with generally some water. 
Queensland opal, when of sufficient size, fire, and free from 
flaws, is a very beautiful gem, but unfortunately only occasionally 
can large pieces of the proper lustre or fire be found without 
flaws. On the Bulloo and Barcoo Rivers precious and fire opals 
are found, and I am told by a leading goldsmith and merchant of 
precious stones that the rash and unscientific way in which the 
lumps ate broken is one reason for the small amount of useful 
opal which is obtained. Common opal, and even precious opal, 
in thin streaks or veins occur in a matrix of a kind of dark clay 
porphyry, and I heard it assigned as a reason for this thinness and 
want of fire that the opal is not old enough ; but I fancy it would 
be more correct to say that the crevices or fissures, into which the 
solution containing silica entered, were only very narrow, or that 
the amount of the silica-depositing solution was limited. 
Common opal and fire opal are found about Springsure, com- 
mon opal being also met with near Gympie ; on the Glasshouse 
Mountains ; and on the Burnett River. Pieces of opal are not 
unfrequently found in the gravel of the Logan River, being 
probably brought down from Mount Lindsay or other adjacent 
ranges. Wood opal occurs at Springsure and on the Dawson 
River. Hyalite occurs at Springsure, at Cumkillenbar, and at 
Stanthorpe, fine specimens from the latter locality shewing hyalite 
coating crystals of smoky quartz and orthoclase felspar. 
X.—ANHYDROUS SILICATES. 
WOLLASTONITE—Comp. chiefly silicate of lime. 
Said to have been noticed on the Pine River. 
ACTINOLITE—Comp. chiefly silicate of magnesia, lime, and a 
little iron. 
Green radiating actinolite has been found in the Cloncurry 
district. 
HoRNBLENDE—Compp. chiefly silicate of magnesia, lime, iron, 
and alumina. 
Hornblende is a rock-forming mineral of frequent occurrence, 
as in the syenitic rock of Charters Towers Hill, where mica is rare 
and hornblende abundant, and at Mounts Frederick and Alice, 
Charters Towers, where hornblende crystals with crystals of tri- 
clinic felspar and round blebs of quartz are scattered through a 
dark grey matrix of felspar with magnetic iron. The No. 1 Lode 
E 
