BY W. N. BENSON. 545 



)>hosed of all the slates described. The felspathic and the aufeii 

 slates cannot be regarded as products of contact-metamorphism, 

 but rather of regional metamorphism; the sediment from which 

 they were formed was not identical with that which has now 

 become blue slate. 



The other types of slates not mentioned above are merely the 

 products of the weathering of the blue or knotted slates. 



vi. — The Llmestones. 



The limestones occur in a group of lenticular beds near the 

 Caloola gold mines, and some eight miles east of Newbridge. 

 They were geologically examined by Mr. L. F. Harper* and 

 economically reported on by Mr. A. L. MacCredie.f The 

 greater part of them is leased to, and worked by, the Common- 

 wealth Marble Quarries, Ltd. Five occurrences may be noted 

 there, as under the number of each description referring to its 

 position on the appended map (Plate xxiii.). 



i. (Portions 104 and 115 of the Parish of Lowry). This is the 

 seat of the main quarrying operations. The patch of limestone 

 is a])out one-quarter of a mile long in a N.N.E. direction and five 

 or six chains wide. It is composed of almost pure, white, 

 crystalline marble; the grain-size is very even, about 1mm. The 

 marl)le is very solid, there being but few cracks or "dryers," so 

 that large blocks are easily obtained. Along the dryers are 

 dendrites, flakes and tufts of sericite, and occasionally crystals of 

 chalcopyrite, galena, and actinolite, metasomatically replacing 

 the limestone. In places the stone is completely replaced by a 

 soft green steatite, fibres of which penetrate into the calcite 

 grains. Microscopically, this seemingly homogeneous green mass 

 is shown to be composed of practically colourless fibres of chlorite, 

 recognised by its low double refraction, small optical axial angle, 

 and optically positive character. There is also a little strongly 

 birefringent talc or sericite, frequently in radiate groups, some 



* Ann. Rept. Dept. Mines New South Wales, 1904, p.l47. 

 + C.M.Q. Ltd., Prospectas. 



