8G NOTES ON SOME MINERALS. 



to translucent ; too small to admit of Sp. G. being taken, but 

 aggregates from druses gave Sp. G-. 3.19. Brittle, easily fusible to 

 a blebby glass. The crystals have more complicated terminations 

 than those from Bowling Alley Point* (see figure 12). The 

 massive garnet referred to constitutes a large vein in the serpentine 

 rocks of the locality. 



Rhodochrosite (Mn Fe CO 3 ). 



At Webb's Lode Silver Mine, near Emmaville (N.E.), in leafy 

 and granular aggregations, at times two inches in area ; also in 

 small globular forms, seldom larger than an ordinary pin-head. 

 In veins and small drusy cavities in the lode stuff; associated 

 with and often seated upon crystals of quartz, and more rarely on 

 crystals of galena, blende, tetrahedrite, lollingite, mispickel or 

 fluorspar. Colour, pale nankin-yellow to brownish-yellow. 

 Hardness about 3. Effervesces with HCL, and reacts for iron 

 and manganese. Not very plentiful. The mineral veins of this 

 locality are in hard splintery jointed argillaceous slates, which 

 are in some places very much altered. 



Siderite. 



At Big Plain, on road from Inverell to Warialda, lining 

 cavities in basalt, from the Government Well. In rhombic 

 crystals with curved faces ; crystals small, not more than -fa inch 

 square. Colour, yellowish-brown, reddish-brown, grey : opaque, 

 but thin splinters transparent. BB. decrepitates, does not fuse, 

 but becomes black and strongly magnetic. In fine powder 

 effervesces with warm HCL With borax and microscomic salt 

 dissolves slowly, giving an iron reaction only ; with soda on 

 platinum foil, trace of manganese. A globular form of this 

 mineral (Spherosiderite) is present with the crystalline variety, 

 and occurs in masses half-an-inch across ; some of the spheroids 

 have a radiated structure, but are often composed of concentric 

 coatings. Spherosiderite also occurs in basalt in the Emmaville 

 District. BB. and with reagents, behaves same as siderite. 



Calcite. 



Deposits of calcite are common in the limestone formations, 

 which extend with few breaks, from the Isis River, thirty miles 

 south of Nundle gold-field, to Bingera, sixty miles in a northerly 

 direction from Tarn worth. Often in concentric aggregations or 

 in stalictitic forms, also compact and cleavable. Colour, reddish, 

 brownish, grey, nearly white. Translucent to opaque ; not 

 transparent. 



*See Proceedings Royal Society, N.S.W., 1884, Vol. xviii. 



