166 Scientific Proceedings, Royal Dublin Society. 



observed ; these were not found to be any richer in the black 

 sand than the ordinary sand of the cliff, the black colour being 

 due to manganese. 



All the samples taken from the cliff were found, on washing, 

 to contain a large quantity of shell fragments, large flakes of 

 mica, and fragments of quartz. The drift from which these samples 

 were taken consists of an irregularly stratified gravel and fine 

 sand, with patches of a stiff marl appearing through it, and is 

 overlaid by a stiff strong clay. From the very irregular manner 

 in which this drift is stratified, and from the oblique lamination 

 of the beds, it seems probable that during its accumulation there 

 were very varying currents. 



In a sample, consisting of about six pounds, of this arenaceous 

 drift, the black sand weighed four grains. 



It seems, therefore, that the black sand occurs sparingly, though 

 widely disseminated through this drift, and that its accumulation 

 on the beach is caused by the waves, during certain gales with 

 high tides, washing away the drift cliffs, and sorting the materials 

 according to their specific gravity. It is also very possible that 

 rich layers, or beds, of this sand may occur through the drift, pro- 

 bably towards the base ; but none were observed. 



When washing, the samples were first passed through sieves 

 which separated them into five degrees of fineness ; each of these 

 was washed in a shallow pan, recognizable mxinerals being picked 

 out during the process, the gold being found in the residue or 

 tailings. These tailings usually had a specific gravity of about 

 5-0 to 5-2. 



The sand yielded about 21-5 per cent, of magnetic material, of 

 specific gravity 4-8, containing magnetite, chromite, and ilmenite. 



In the tailings, after the extraction of the specks of gold and 

 magnetic portions, the following minerals were recognised, viz. : — 

 Cassiterite in small grains ; red haematite, tolerably abundant ; 

 brown haematite ; iron pyrites, rarely unaltered, but there are 

 many small cubes either partly or wholly altered into brown 

 iron ; rutile, rare, only a few specks being detected ; besides 

 quartz, both rose-coloured and of a light yellow; garnets, very 

 numerous and many-coloured, including various shades of green, 

 yellow, and red. There are also some fragments that appear to 

 be zircons. 



