Blt a a 
ON THE EXPLORATION OF KILIMA-NJARO. 683 
of scoria, evidently picked up by the molten rock. These resemble an 
andesite, being full of plagioclase microliths, and one of them contains 
two larger broken plagioclase crystals. 
(c) Isa very compact, almost black rock, without vitreous lustre. 
Examined with the microscope, it is seen to be very similar to the last, 
except that the separation of the minerals has proceeded a little further ; 
the opacite granules and felspar microliths being slightly larger. There 
are one or two crystals in the slide of larger size; felspar, broken looking, 
-magnetite and apatite. 
(2) Central Ridge, Kilima-njaro, 14,000 feet (7 specimens of rock, 
1 mineral).—Of the rock specimens (a) two are rather rounded; a very 
compact, dark grey, almost black rock. (b) Three flattish, rather 
scoriaceous fragments, two of them having a very marked platy structure, 
so that at first sight they might be taken for stratified. (c) Two are soft 
fragments of a dark brown compact rock (seemingly rather decomposed), 
containing crystals, more than half an inch in diameter, of a rather glassy 
felspar. 
(a) I have examined slices from each of these. One of these differs 
very little from that last described, 1 (c), except that there seems to be a 
general tendency to form minute spheroids (without a radial crystalline - 
structure), coated externally with a film of iron oxide. The other 
specimen belongs, no doubt, to a similar rock, as its glassy base is now 
crowded with elongated microliths of a plagioclastic felspar and granules 
of magnetite. The slide contains two crystals of brown hornblende, one 
or two crystals of nearly colourless augite, and a few minute patches, pro- 
bably of brown glass. (b) I have not examined these microscopically, as 
they appear to me only more scoriaceous forms of (a). (c) One of these 
has been examined. The ground mass has a general resemblance to that 
of the first specimen in (a), but appears rather more decomposed. In 
this occur a few grains of a nearly colourless mineral, some certainly augite, 
though olivine may also be present. The former appears once or twice 
to have been more or less replaced by magnetite, which mineral also 
occurs in independent crystals, and there is a little apatite. The large 
felspar crystals, two of which are partly included in the slide, are worn 
and rounded at the edges and have several inclusions of the ground mass. 
They present a general resemblance to sanidine. 
The separate crystal of a mineral has evidently been detached from a 
similar rock ; it is about four-thirds of an inch long and rather more than 
half an inch wide. It bears a general resemblance to sanidine, but the 
form is a very peculiar one for this mineral to assume. ‘The faces of 
co P are well developed, OP rather small, together with another face in 
the vertical zone; oo Roo small. Distrusting my own opinion, I referred | 
the crystal to my friend Mr. T. Davies, of the Mineral Department of the 
British Museum. He at once intimated that the form was very unusual, 
and, after consultation with the other officers of the department, wrote to 
me that the crystal was a variety of orthoclase. This, with some others 
mentioned below, will, I hope, be described more at length by Mr. Miers 
at the next meeting of the Mineralogical Society. 
Stones of Kimawenzi (3 specimens).—These specimens appear to be of 
a very similar rock, and are all more or less decomposed. They are 
practically identical with 2 (c), so I have not had a slide cut. They also 
contain good-sized crystals of the same peculiar felspar. 
Stone, base of peak, Kimawenzt, 14,700 feet—Slab about 64” x 44! x 4” 
