MINERALIZED WITH SILICATES. 61 
ever, tend rather to the latter view, as would also the chemical cha- 
racters of the serpentine already referred to; but the association 
with fossils mentioned below tends to show that at least a part of 
the mineral is an ordinary aqueous deposit. It is also to be ob- 
served, with reference to the superposition of serpentine on fossilife- 
rous Lower Silurian rocks, that a similar relation is affirmed by 
Murray to occur in Newfoundland, where massive serpentines overlie 
unaltered fossiliferous rocks of the Quebec group*. 
No fossils have been found in the compact serpentine, but only 
in the limestone paste of the brecciated masses and in the limestone 
bands interstratified. The limestone of the breccia contains not only 
angular fragments of serpentine but disseminated serpentine and 
small veins of the same mineral. Its fossils are limited to small tu- 
-bular bodies, crinoidal joints, and fragments, apparently of Stenopora, 
very imperfectly preserved. ‘The tubular bodies may be portions of 
Hyolithes or Theca. Their interior is usually filled with dolomite ; 
their walls are in the state of calcite; and they are incrusted with 
an outer ring of serpentine. In some instances the calcareous 
organic fragments are seen to be filled in the interior with serpen- 
tine. The crinoidal fragments are in a similar condition, the ser- 
pentine having apparently surrounded them in a concretionary 
manner after the cavities had been filled with dolomite. Frag- 
ments of calcite, dolomite, or older serpentine included in the lime- 
stone, and of no determinate form, are enclosed in the new or re- 
manié serpentine in like manner, and in some cases this newer or 
coating serpentine was observed to have a fibrous structure. The 
serpentine thus coating and filling fossils and fragments is of a 
lighter colour than the serpentine of the fragments themselves, and 
in this respect resembles that of the small veins traversing the lime- 
stone. Such traces of fossils as exist in the layers of limestone are 
similar to those in the breccia, but not, so far as observed, coated 
with serpentine. 
It would thus appear that, contemporaneously with the original 
deposition of the serpentine, thin bands of limestone were laid down, 
with a few fragments of crinoids, corals, and shells; that subse- 
quently, but perhaps within the same geological period, and while 
the deposition of serpentine was still proceeding, portions of the 
surface of the serpentine were broken up and imbedded in limestone ; 
that the fissures of this limestone were penetrated with serpentine 
veins, and its few fossils coated with that mineral, which also forms 
flocculent laminee in the limestone. : 
The mode of deposition of this Paleeozoic serpentine is thus con- 
siderably different from that of the Laurentian, which forms layers 
intimately interstratified with great limestones, and also nodules, 
concretionary grains, and fillings of fossils in these limestones. This 
difference in mode of occurrence is, no doubt, connected with the dif- 
ference in composition of the two varieties of the mineral already 
noticed. In both cases, however, the serpentine has been so depo- 
* Bedded serpentines also occur in unaltered Silurian dolomites at Syracuse 
in New York (Hunt, Chem, and Geol. Essays, p. 310). 
