24 THE VICTORIAN NATURALIST. 



gives the characteristic extinction-angle measurement on the 

 face ooi. 



Augite. — Fairly frequent in both samples as broken crystals or 

 shapeless fragments. A few perfect crystals were found, which 

 give oblique extinction, are feebly pleochroic, and show the 

 approximate right-angled cleavage, tjsually of a pale or dull 

 green colour, but sometimes greenish to smoky-brown. 



Actinolite. — A crystalline aggregate of this mineral, which 

 approaches Tremolite in its pale colour, was found in the 

 St. Kilda material. It is fibrous, pale green, and faintly 

 pleochroic. 



Tourmaline. — This mineral occurs in both samples of the 

 sediment, and the crystals are frequentlv perfect and doubly 

 terminated. They are easily recognized by their strong 

 absorption and straight extinction. One crystal from the 

 Camberwell fall is of a pale indigo-green ; the others are usually 

 smoke-brown to greenish-brown. 



Olivine is somewhat frequent in the St. Kilda material of 28th 

 March. The grains are sharply broken, and show a conchoidal 

 fracture. Amongst other characters their polarization colours 

 serve to distinguish this mineral from quartz. 



Garnet. — A single isotropic granule of a pale pink colour 

 occurred in the St. Kilda sample of 14th February. 



Cordierite. — An angular piece of this mineral species was 

 found in the St. Kilda sample, and is the only specimen met 

 with after a careful search. It gives the characteristic colours of 

 blue to yellow when examined with the polarizer only. It is met 

 with in both granites and gneisses in Victoria. 



Butile. — Occasional, in the St. Kilda material. Crystals some- 

 what rare, varying from dark yellowish-brown to deep red-brown. 

 No twinned forms observed. 



Zirco7i. — A rounded crystal of colourless Zircon, measuring 

 .04 mm. in length, was found in the Camberwell sediment. 

 Found more commonly in the St. Kilda material. 



Apatite. — A crystal measuring .06 mm. in length occurred in 

 the Camberwell sediment. 



Epidote — A doubly-terminated crystal from the Camberwell 

 fall, measuring .09 mm. in length ; viewed through axis c it gives 

 greenish-brown. Also strong refraction, with edges in high 

 relief. Incipient fractures nearly at right angles to ortho- 

 diagonal. 



Nalrolite (?). — A fragment of a radially-grouped mineral, from 

 St, Kilda, giving straigiit extinction, and resembling Natrolite in 

 its general characters. 



Limonite. — Numerous rounded flakes of a reddish-brown or 

 yellow colour are seen to be disseminated through the mounted 

 material, and to which, together with the more powdery or 



