i^naljjsis of ^okanit ^sljes from i\^t 



^akmxk €nx^imx at |,^rahatoa 



m 1883. 



By ALFRED C. FRYER, Ph.D., M.A., F.C.S. 



SOME observers remark that the Krakatoa eruption 

 yielded labradorite, augite, magnetite, and apatite. 

 Others state that hornblende and iron pyrites were also 

 found. The principal mass of the ashes consists of a glass 

 crowded with minute cavities. The larger pieces readily 

 floated on water. The glass is generally colourless, but 

 more or less brown. Microliths were occasionally met with. 

 The cavities in the glass were sometimes round, and some- 

 times drawn out in a longitudinal direction. In addition to 

 the glass, many more or less perfect fragments of crystals 

 were observed, consisting principally of plagioclase and 

 bronzite, together with small and rather narrow prisms of 

 a greenish m.ineral, probably augite, and apatite. It has 

 been pointed out that this youngest eruption-product from 

 the Straits of Sunda bears the andesite character so general 

 in the district, and is of special interest on account of the 

 presence of rhombic pyroxene. 



A small quantity of the ashes which fell in Batavia was 



44 



