BY EDWD. B. LINDON, A.R.S.M. 67 
i situ. A coarsely crystalline granite in the S.E. corner of the 
Great Northern P.C., Herberton, consists of black mica with 
quartz and pink orthoclase. 
LABRADORITE—Comp. chiefly silicate of alumina, lime, and soda. 
Mr. R. L. Jack mentions that he found labrador felspar of the 
beautifully iridescent variety used in jewellery, in a valley in the 
west of Mount Eurie, near Cloncurry. 
OrTHOCLASE—Com, chiefly silicate of alumina and potash. 
Very fine crystals of orthoclase, associated with smoky quartz, 
occur in the neighbourhood of Stanthorpe and Ballandean, some 
of the crystals being enveloped by hyalite. 
Orthoclase felspar is a very common rock-forming constituent, 
as at Running Creek to the west of the Great Star River where 
the porphyry is coarse with large round quartz blebs, large crystals 
of orthoclase, and occasionally a little hornblende, mica being 
very rare. Pink orthoclase forms part of the granite at the Great 
Northern P.C., Herberton, and at the Pinnacle Lease, Gregory’s 
Gully, in the same district, the same coloured mineral forms the 
matrix of cassiterite. 
OLiIGocLaAsE—Comp. chiefly silicate of alumia, soda, and lime. 
Triclinic felspar is a not very frequent constituent of Queens- 
land rocks, being very often only detected by microscopic 
examination of thin sections. 
‘TOURMALINE— Comp. chiefly composed of silicate of alumina, iron, 
lime, and soda, and containing some boric acid. 
Occurs in quartz on St. John’s Creek, Burnett district, and at 
Cloncurry, where it is found with free gold scattered through its 
mass and with calcite as an associate. Schorl and calcite form 
the matrix of an auriferous pyrites in the Union Gold Mining 
Co.’s lease, Rockhampton. Quartz containing tourmaline and tin 
ore occurs in the Day Dawn claim, ‘linaroo district. ‘Tourmaline 
porphyry is not an uncommon rock in the colony, as at the 
Normanby Range, near Bowen, which “consists almost entirely 
of this rock, a compound of quartz (for the most part amorphons), 
black mica (sparsely), and large black crystals of tourmaline or 
schorl” (Jack). Black schorl is also said, by Mr. D’Oyley Aplin, 
to occur in the firte-grained felspathic rock in the lower part of 
the Stuart Valley, Burnett district. Tourmaline also occurs at 
Mount Perry. 
