674 GREAT SERPENTINE BELT OF NEW SOUTH WALES, Hi., 



antigorite-flakes growing out perpendicularly from a central 

 crack, and stabbing into (clearly replacing) the dusty portions. 

 Some pseudomorphs of bastite present, are also being replaced in 

 the same manner, but the process has not gone on so far. Grano- 

 phyric chromite is also present. 



An interesting series of slides shows the successive steps in the 

 replacement of normal mesh-structure serpentine by antigorite. 

 An early stage is shown in N.T., 258, from Munro's Creek. This 

 rock is a harzbergite, so poor in pyroxene as to pass almost into 

 the dunites. It has first been serpentinised in the normal 

 manner, and the typical mesh-structure is well seen, accompanied 

 by the usual disposition of the lines of magnetite-particles. The 

 pyroxene has passed into bastite. The rock is traversed by 

 major cracks, marked by a plentiful amount of magnetite-dust, 

 on either side of which, the normal serpentine has been recrystal- 

 lised as antigorite, forming large flakes parallel, transverse, or 

 inclined to the direction of the vein, and stabbing, dagger-like, 

 into the brownish mesh-serpentine on either side. Here, again, 

 the replacement of the bastite is not so far advanced (Plate xxvi., 

 fig.8). 



More advanced in this alteration, is N.T., 383 (Plate xxvi., 

 fig.9), a massive serpentine from the Razorback, in Munro's 

 Creek. The rock was a bastite-serpentine. The whole of the 

 ground-mass has now become antigorite, disposed in small plates 

 aggregated into sheaf-like bundles, spreading and fraying out at 

 either end. Often two sheaves cross one another at right angles, 

 their separate elements appearing as if interwoven, while the 

 outer portions may spread so widely as to give the whole mass 

 the appearance of a spherulite. The large bastite-plates are still 

 present, but in them, also, the change to antigorite is in process. 

 The mineral is arranged in similar though large sheaf-like masses, 

 single or crossed, the warp and woof of the matted plates being 

 very distinct. Single flakes of antigorite also occur, with their 

 characteristic, sharp, dagger-like outline in the bastite ground- 

 mass The position of the strings of magnetite-particles alone 

 remains to show the original mesh-structure of the matrix of the 

 rock. A little chromite and carbonates are present. The 



