BY W. N. BENSON. 713 



peculiar. The former contains a ground-mass of finely-divided 

 quartz and green omphacite, with a little felspar and bands of 

 coarse oligoclase, wollastonite, irregularly shaped diopside and cal- 

 cite. A few, large, clear plates of scapolite are present. Irregular 

 patches of sieve-like garnet occur in the ground-mass, full of inclu- 

 sions of diopside, and there is also a little irregularly shaped 

 vesuvianite. 



M.B., 173, is a dark green rock, with lighter, yellowish-green 

 patches, containing small aggregates of macroscopic crystals of 

 epidote and plagioclase. The main mass of the rock consists of a 

 tine mosaic of quartz, with dusty orthoclase and some plagioclase, 

 and much irregularly shaped, partly sieve-like epidote. A little 

 zircon is also present. 



The limestones at CarmichaeTs, near Tamworth, furnish several 

 interesting specimens. Rocks, like N.T., 444, consist of brownish 

 garnet in a grey, silicate matter, set in a matrix of crystalline cal- 

 cite. The silicate matter is made up of very finely divided ortho- 

 clase and oligoclase, quartz, wollastonite, and diopside. The 

 garnets are pale brown, and are filled, sieve-like, with inclusions of 

 the above minerals. In addition, there are small, square patches 

 of more coarsely crystallised wollastonite, frequently associated 

 with a little garnet and calcite. There are also grey-green, silicate 

 rocks, containing coral-fossils (Syringopora*!), the tubes of which 

 have been filled with wollastonite, which, weathering more quickly 

 than the main mass, exposes the markings on the coral tube-walls, 

 in naturally etched specimens. The matrix differs from the last 

 rock in containing green omphacite. 



The rocks that occur on Horsearm Creek, near Attunga, are most 

 handsome. They are chiefly composed of a cinnamon-brown gar- 

 net, frequently forming idiomorphic crystals. They are charged 

 with chalcopyrite, which decomposes to azurite, colouring the rock 

 very brilliantly. Certain parts of the rock become dark or black 

 by the development of much magnetite with the chalcopyrite. One 

 of the rocks [M.B., 128] consists chiefly of brown or reddish gar- 

 net, very irregular in outline, and full of inclusions of calcite, 

 hornblende passing to chlorite, small plates of brown mica, chlori- 



