ce a 
‘ROCKS FROM NEW BRITAIN AND NEW IRELAND. 51 
Gypsum, also found in the crater with the sulphur, in the form 
of acicular crystals 
Aragonite.—In the form of nodular masses, seen on fracture to 
be built up of beautiful transparent columnar crystals arranged in 
aradiate manner. They look as if they had been set free from 
amygdaloidal cavities in igneous rocks. 
Limestone.—White, granular. 
rtz.—OFf a chalcedonic character. 
The rolled pebbles of porphyry, epidote rock, and others of the 
crystalline rocks from New Ireland indicate the presence of much 
more ancient rocks in that island than do any of those examined 
ew Britain ; they cannot, however, without further evidence, 
be assigned to any particular geological period, for such metamor- 
y of the older series. Most 
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parently of comparatively recent geological origin ; some of the 
Specimens of limestone may even be of existing coral growth, but 
there is no trace of organic structure remaining to indicate the 
age of the rock, the structure being suberystalline. 
e igneous rocks are all doubtless modern voleanic products. 
