BY C. A. SUSSMILCH AND H. I. JENSEN. 189 



The former type is represented by a slide of a black-grained 

 basalt from Norris's Farm, The Canobolas. The felspar forms about 

 ^5°/^, and occurs as laths, varying in composition from albite to 

 acid labradorite. Augite, of a brown to puce colour, in rounded 

 allotrimorphic grains, and its decomposition-product, chlorite, 

 occur to the extent of about 15%. Olivine alone occurs as pheno- 

 crysts ; it is decomposing to serpentine. Small red, rounded 

 grains of fayalite are also present. These peridotic constituents 

 form about 10°/^. Ilmenite forms about 7%. The balance 

 consists of an isotropic, light-coloured residuum, probably con- 

 taining analcite, and apatite needles which penetrate the felspars 

 and base alike. 



This rock is probably an alkaline basalt. Mr. Mingaye's 

 analysis^* (i.) of Canobolas basalt, probably represents this rock- 

 type. 



The olivines have frequently felspar-laths penetrating their 

 outer portions. 



Order of consolidation. 



Ilmenite 



Olivine 



Apatite 



Felspar 



Augite 



Analcite {1) glass 



This rock is a hyalopilitic oli vine-anal cite (?) basalt. 



The Melilite Basalts. — The basalt from the Racecourse Quarry, 

 near Orange, is a dark rock of t3''pical basaltic appearance. 



Texture: holocrystallinej fine and even-grained, with pilotaxitic- 

 ophitic fabric. 



Constituents (in order of decreasing abundance): felspar, 

 angite, olivine, melilite, ilmenite, magnetite, and accessory apatite. 

 The prismatic microlites of felspar penetrate the augite grains 

 ophitically, and form frames round the augite, giving microtine 



* Records Geol. Surv. N.S.Wales. 1904, Vol. vii. 



