198 Jounston-Lavis— The Eruption of Vesuvius in April, 1906. 
The chlormanganokalite is in beautiful crystals, some attaining 5 mm. to 1 cm. 
in diameter, and are superposed on the halite and sylvite. In another block, 
in which fumarolization had converted the whole mass into a lemon-yellow mass, 
chlormanganokalite crystals are over a centimetre in diameter, but are damaged 
by a coating of some iron-chlorides. Here again this mineral is associated with 
erystals of the alkaline chlorides, and with a rare form of hematite, in brilliant 
spear-like-looking crystals, which Mr. J. L. Spencer, who has measured them,* 
finds to be acute scalenohedra, exhibiting the following faces :—{313} = {2461}) 
or the form £8 of text-books. 
This hematite afforded me the following composition :— 
Insal. in nitro-hydrochloric acid, . 4:784 (attached silicates). 
Fe,O;, . ; 3 : s  SeleOil 
5, . : : : ° : - _0°452) Probably adherent 
As, ) . ‘ traces] Sulphur of realgar. 
This form of hematite is quite new to me at Vesuvius, neither do I know of 
its ever being detected before. Such forms of hematite are, so far, known as 
occurring at an ‘island in the Red Sea.” The crystals are distinctly magnetic. 
Zambinellit very fully described the minerals that have formed by sublimation on 
the lava-flows. 
Sal Ammoniac was abundant, as crusts, around fumaroles scattered over the 
lava-streams, where these had flowed over ground containing organic matter, 
confirming the old theory that this mineral is derived from the decomposition 
of such matter, and its ammonia being converted into a chloride by the hydro- 
chloric acid escaping from the lava.t Halite and sylvite, in varying proportions, 
were likewise deposited around fumaroles and cracks, and in some places were 
associated with iron-chloride and various other chlorides. These were still 
being deposited on the lava at Boscotrecase in November, 1906. 
Hematite in the usual scales, and small crystals, were to be met in the scoria 
near the fumaroles of the lava. Cotunnite was also said to be found; and though 
I received specimens as having been so found, I did not see or collect them 
myself. 
Chlormanganokalite, a New Vesuvian Mineral’’; with notes on some of the associated minerals. Min. 
Mag., vol. xv., No. 68, April, 1908. 
* H. J. J.-L. and L. J. Spencer, Min. Mag., vol. xv., No. 68, pp. 54-61. 
t Op. cit. 
{See an interesting crystallographic study by F. Slavick, Bull. Internat. de l’Acad. des Sc. de 
Bohéme, 1907, 
