THE VICTORIAN NATURALIST. 



periphery was acute. Both surfaces were rough and pitted, as 

 though etched in a regular manner and having relation to some 

 inherent crystalline strain. These hail-stones averaged lo mm. 

 in height. 



In connection with the following notes on the sediment of 

 the red rain an opportunity has been taken to examine 

 a sample of dust which had drifted on to the skylight of 

 the National Museum, Melbourne. The material, in some 

 respects, was comparable with the ordinary sediment of the 

 mud-rain, but of a somewhat coarser nature, the greater 

 part being mineral grains, and only a few fragments of 

 diatom frustules were seen. It differed also in containing 

 minerals of a distinctly local character, presumably derived 

 from the powdering of the road metal in the district, such 

 as basalt and limestone. 



The Minerals found in the Two Samples of Red-rain 



Sediment. 



Sediment in the mass reddish-brown. 



Quartz. — This is by far the commonest mineral in both samples 

 of red-rain sediment. The particles are usually quite angular, a 

 small proportion only being sub-rounded ; and these latter are 

 not so smooth and polished as in the case of the desert sands of 

 the interior, typical examples of which, obtained during Professor 

 Gregory's recent expedition to Lake Eyre Basin, we have 

 compared for the purpose. Some of the grains from the sediment 

 are indeed sharply angular as if freshly crushed or broken, as 

 would be the case if some of the material were derived from dried 

 tailings and sluicings, such as occur abundantly in the mining 

 areas to the north and north-west of Victoria. 



The thickness of the quartz grains may be judged by their 

 polarization colours ranging from iron grey to straw yellow of the 

 first order of Newton's colour scale. Some of the quartz 

 fragments are clear, but the majority are more or less crowded 

 with cavities and bubbles. 



()])al is represented by a flake of a pale-brownish colour giving 

 a dark extinction cross, due to inherent strain. 



Orthoclase felspar is rather rare ; some perfect crystals, how- 

 ever, were met with, one being twinned on the Carlsbad type. A 

 good specimen of a zoned Orthoclase occurs in the St. Kilda 

 sediment. Fragments of larger crystals of Orthoclase are fairly 

 abundant, showing schiller structure developed normally to tlie 

 pinacoid faces. 



Sanidine is frequent in the St. Kilda material (28th March). 



Alhite is not common, but occurs in small angular chips in 

 both samples (from St. Kilda and Camberwell). 



Anorthoclase is rare in the St. Kilda sample (28lh March), It 



