THE VICTORIAN NATURALIST. 31 



Alhite rare, witli fine repeated twinning. 



Lahradorite frequent, with extinction angle about 32°. 



A fragment oi Anorthite\va.s found having a maximum extinction 

 angle of 58°. 



Augite. — A pale green variety very common ; the majority in 

 fragments, but several perfect crystals present. Two pieces of 

 brown Augite with inclusions of magnetite crystals, showing 

 the occurrence of parallel grouping of octaliedra. One Augite 

 crystal of a purplish-brown colour. 



Tourmaline. — Common. Some good slender prismatic 

 crystals. 



Olivine. — Irregular granules, with rough surfaces and strongly 

 refractive edges, very common. 



Garnet very rare. Pink, isotropic granules. 



Rutile. — Frequent, generally fragmentary or in short rounded 

 crystals ; also as included crystals in quartz. 



Cassiterite (?). — Cleavage fragments yellow or yellowish-brown, 

 and showing an anomalous interference figure, are frequent. 

 They agree most in character with the above mineral. The 

 fragments, when imperfectly cleaved, show a curious rippling of 

 the surface, like that of amethystine quartz. Their colouration is 

 too strong for citrine. 



Zircon. — Frequent, more or less rounded. 



Epidote. — As an alteration product in felspars, frequent. 



Zoisite. — Penetrating fragments of felspars as Labradorite. 



Calcite in rhombs, rare. 



Magnetite. — Irregular granules frequent. 



Limonite. — In less proportion than in the red rain sediment ; 

 also as included crystals of octahedral form in Augite. 



Besides the minerals enumerated, occasional exanijiles of 

 opaque spherical bodies were met with, resembling those found 

 in deep sea deposits, and referred to as cosmic dust. 



There were also numerous translucent greenish-brown glassy 

 spheres, with granular inclusions and bubbles. These latter 

 measure about .05 mm. in diameter. 



Numerous particles of soot were present, undoubtedly of local 

 origin. 



By far the larger part of the Melbourne dust consists of particles 

 having a distinctly local origin. Among the minerals the con- 

 stituents of basalt and other rocks, and possibly limestone, are 

 very much in evidence. 



Among the organic constituents remains of rotifers and a ^ew 

 broken valves of diatoms of the larger species were noticed. 



