62 
SPOLIA ZEYLANTCA. 
The following analysis was made at the Imperial Institute*: 
ai 2 o 3 
... 17-88 
Fe 2 0 3 
0-21 
Mg 0 
... 25-86 
Na 2 0 
1-09 
k 2 0 
9*90 
Si0 2 
... 39-39 
h 2 6 
... 3-62 
Moisture 
... 084 
98 : 79 
IV.— Kyanite. 
“On Sea-bottoms and Calcretes” J. Lomas, in Professor Herd- 
man’s “ Report on the Pearl Oyster Fisheries,” Roy. Soc., London, 
1903. 
Kyanite was found by Mr. Lomas as a constituent of sands 
dredged by Professor Herdman off the coast of Ceylon in 1902; 
the mineral has not previously been recorded from Ceylon. 
In Galle Bay were obtained the minerals, quartz, kyanite, 
corundum, rutile, tourmaline, and mica ; in Trincomalee Bay, 
quartz (magnetite), garnet, corundum, tourmaline, kyanite, mica ; 
inPalk Bay, quartz,tourmaline,felspar, zircon,corundum,kyanite, 
mica, ilmenite ; in various parts of the Gulf of Mannar, quartz, 
ilmenite, magnetite, tourmaline, zircon, garnet, kyanite, rutile. 
These minerals have no doubt, as pointed out by Mr. Lomas, 
been brought down by rivers from the higher parts of Ceylon, and 
distributed by currents over the ocean bottom. The absence from 
these lists of spinel and sillimanite is rather curious. 
V.—Chert and Opal. 
I have recently shown (Geol. Mag., 1904, Dec. v.,Vol. 1, pp. 16-19) 
that at any rate a part of the chert and opaline rocks which are 
locally, but in moderate abundance, distributed in the parts of 
Ceylon with which I am acquainted, are alteration products of 
crystalline limestones, the carbonates having been removed in 
solution and replaced by chalcedonic and opaline silica, so that we 
may find cherts containing the original accessory minerals (spinel, 
phlogopite, graphite, apatite) of the limestones, but showing no 
trace of the original carbonates. In other specimens relics of the 
partially removed carbonates are to be seen. This corresponds to 
what we know of many cherts that occur amongst sedimentary 
rocks in England, where it has been shown that the silica (what¬ 
ever its source) has replaced the original carbonates, which appear 
to have been corroded and removed in solution. In Ceylon the 
process appears to have taken place long after the formation of 
the rock itself. 
* I am sorry that the names of the individual chemist or chemists by whom 
some of the analyses quoted were made have been withheld, and cannot therefore 
be given. 
