W. R. Jones—Tin-mining at Ulu Bakau, F.MS. 4538 
Savona region between the calc-schists and pietre verdi in the north- 
eastern part and those of the Bormida Valleys on the western margin 
is only about 15 kilometres; it may, therefore, be legitimately 
assumed that the gap was simply eroded, that both the Triassic 
formations—dolomitic limestones and cale-schists with pietre verdi— 
originally extended from the Maritime Alps continuously to the 
Voltri group, and that the latter, of submarine sedimentary and 
eruptive origin, was formed 7m situ rather than by an overthrust 
from the west. In either case itis, by reason of its Mesozoic age, 
geologically Alpine in character, and constitutes, together with the 
Savona crystalline massif, the contact-zone of the Alps and the 
Apennines. 
V.—Munine In THE Feperatep Matay Sratss. 
[In the GEOLOGICAL MAGAZINE for June last, p. 255, Mr. W. R. Jones 
refers to a Preliminary Report of Mining in the Mam Granite Range, 
Federated Malay States, 1913. This report bore a slightly different title, and 
was not published. It is the property of the Federated Malay States Govern- 
ment, but I have the permission of the Chief Secretary to forward to you 
a typescript marked ‘‘ Office Copy’’ and initialled by Mr. Jones, and to ask 
you to publish that portion of the report which refers to Gunong Bakau.— 
J. B. SCRIVENOR, Geologist to the F.M.S. Government. 
GEOLOGIST’S OFFICE, BATU GaAJAH, July 14, 1916.] 
Pretiminary Repvort on Tin-mininc on tHe Matin Ranee at Utu 
BaKavU AND NEIGHBOURHOOD. 
Hemy’s Lode, Ulu Bakau (Sungei Bakau Mine).—At a height of 
about 4,500 feet tin-ore is found in this mine in undecomposed 
granite which has to be crushed by foot-stamps before the cassiterite 
can be recovered. The rock is a medium-grained granite, very rich 
in quartz, muscovite, and cassiterite, and relatively poor in felspar. 
Microscopic sections show that the greenish colour, so noticeable when 
the rock is wet, is due to the presence of chlorite formed by the 
alteration of the muscovite and pale-coloured biotite of the original 
granite. The rock here is very different in appearance from that in 
Mr. Bibby’s mine, but agrees with it in the low percentage of felspar. 
An interesting point in a granite so heavily mineralized is the 
small amount of pyrite and mispickel on the one hand, and the 
abundance of tourmaline on the other. I have noticed this in other 
cases, and although the two classes of minerals do occur together in 
the same mine, yet the abundance of one class seems to be at the 
expense of the other class. This is well illustrated in Mr. Bibby’s 
mine, where one part is very rich in tourmaline and topaz, whereas 
the other (the one near the aerial rope-way) is extremely rich in 
mispickel and pyrite. The explanation is that where tourmaline 
and topaz are abundant, the tin-ore came up originally as the vapours 
_ of fluorine and boron; and where mispickel and pyrite are predominant 
the vapours of sulphur and arsenic were the mineralizers. So persistent 
is tourmaline in Mr. Hemy’s mine that the Chinese call it by a name 
which means “‘ the friend of tin’”’, and I have no doubt if they could 
