364 Proceedings of the Royal Society of Edinburgh. [Sess. 
XX. — Contributions to the Chemistry of Submarine Glauconite. 
By W. A. Caspari, B.Sc., Ph.D.. F.I.C. ( Communicated by Sir 
John Murray, Iv.C.B., F.R.S.) 
(MS. received February 3, 1910. Read March 21, 1910.) 
I. Granular Glauconite and its Purification. 
The chemical composition of submarine glauconite is of considerable interest 
in view of the fact that glauconite is the only silicate which is synthesized 
at the bottom of the sea, and apparently nowhere else. Numerous analyses 
of this mineral have been published from time to time,* but the results are 
far from uniform, because the material almost always — certainly in most of 
the older analyses — was anything but pure. The analysis which inspires 
most confidence on this score is one which was recently carried out in the 
Challenger laboratory by Collet and Lee f on a purified granular glauconite 
dredged off the Californian coast by U.S.S. Tuscarora (1879). 
If grains of glauconite could conveniently be removed out of a coarse 
greensand by hand-picking, the preparation of a pure sample would present 
no difficulties ; but such is not the case. The method of isolation adopted 
by Collet and Lee depended on the use of a powerful electro-magnet, which 
extracts the highly ferruginous glauconite and leaves behind the accompany- 
ing quartzose and felspathic minerals. This process is very tedious, and a 
trifling contamination of the product by crystalline matter is inevitable. 
There can be no doubt, however, that the material analysed by Collet and 
Lee represents very pure glauconite. 
Experiments in the Challenger laboratory have now led to a method by 
which glauconite can easily be isolated in a high degree of purity. 
A greensand is first treated with dilute acid to dissolve out calcium 
carbonate, if present, and then washed to remove finely-divided and clayey 
matter. The residue, which now consists solely of glauconite grains plus 
crystalline sand, is digested with hydrochloric acid (f n.) for ten minutes on 
the water-bath, and then for ten minutes with caustic soda (10 per cent.), 
also on the water-bath. Neither reagent attacks the glauconite appreciably, 
but the alkali takes up organic matter and acquires a dark-red colour and 
* No less than 43 analyses are quoted by Leith, U.S. Geol. Survey Mon., xliii. p. 239, 
1903. Many of the specimens, however, are of continental origin, and some are not true 
glauconites at all. 
t Proc. Roy. Soc. Edin., xxvi. p. 259, 1906. 
