Journal of the Federated Malay States museums - Sabrizain.org

32 Journal of the F.M.S. Museums. [Vol. VII,
Mining Industries of Ulu Pahang," p. 59, 60) which are
believed to be of the same age as the granite of that range and
possibly to owe their distinct composition to a mixture of a
basic magma with that of the granite. Some of these rocks,
however, contain pyroxene. There is none in the Pulau
Pisang pebble nor is there any reason to believe that the
hornblende is derived from pyroxene, and a rock of this nature
might consolidate at a shallow depth from a part of a
hornblende-granite magma poor in quartz. There is a quantity
of white opaque matter showing a trace of crystal outline
which is probably a decomposed titaniferous mineral.
j. This is a dark pebble, shown by the thin section to be
altered volcanic ash rich in quartz and with orthoclase and
soda-plagioclase as felspars. Alteration is proved by the hard
compact nature of the rock and the presence of a secondary
mineral, in minute grains. It may be zoisite.
4. Another altered ash similar to 3. The secondary
mineral is probably epidote.
5. A finer grained ash, full of a granular mineral, probably
secondary epidote.
6. A rock with much secondary epidote which obscures
its original nature. It may have been sandstone.
7. A pale grey pebble of very fine but hard texture. It
is impossible to say anything with certainty about its mineral
composition even after examination under a 1/12" oil immersion
objective. It is probably altered shale with minute granules
of epidote.
8. A pebble closely resembling black chert of the Chert
Series, the resemblance being confirmed by the section. The
secondary minerals are epidote, some forming minute veins,
and a very finely fibrous mineral of which nothing definite can
be said but which is probably an amphibole. There is no trace
of radiolaria.
9. A banded pebble showing black and grey rock. Both
are very fine grained but the black rock is certainly altered
chert, while the grey is either shale or fine ash.
ro. This is one of the two specimens mentioned by Mr.
Kloss and is like No. 7. It shows stratification. Thin sections
of the rock point to it being fine shale full of granular epidote.
11. The other specimen mentioned by Mr. Kloss consists
of alternating bands of black and grey rock, the latter having a
slight buff tint. The grey bands resemble 7 and 10 and mav
be either altered shale or fine ash. The black bands are
altered chert and fine black shale. The secondary minerals
they contain are epidote, the fibrous mineral seen in No. 8,
which, in one slide, has a distinct greenish tint, and brown
mica.