King and RowneY— On Serpentine Marble of Shy e. 1 39 
These inferences open out a wide field of speculation in pseudo- 
morphic geology : and it becomes a legitimate question — whether the 
Skye ophite may not have been, previous to its present condition, 
altogether a different rock, essentially composed of calcareo-magnesian 
silicates, which became calcitic, or dolomitic by the elimination of its 
silica, and the replacement of this substance by carbonic acid."^ 
But whatever view may be taken respecting the mineralogical 
characters of the rock under consideration, in its pre-ophitic con- 
dition, we entertain no doubts as to our having fully and clearly 
established the truth of the two following conclusions : — 
1st. That all the microscopic forms characteristic of the Laurentian 
ophite of Canada are more or less paralleled by those occurring in the 
Liassic ophite of Skye. 
2nd. That the microscopic forms in the Skye ophite are the result 
of structural and chemical changes, to which its essential siliceous 
minerals are characteristically liable. 
A few words more. It cannot be too strongly enforced that mala- 
colite, loganite, and serpentine, belong to one and the same class of 
mineral silicates, having a close pseudomorphic relation ; and that they 
consequently represent a series of chemical changes ; also, that dolo- 
mite and calcite, which are similarly related to each other, occur as 
pseudomorphs after mineral silicates. Crystals of garnet, labradorite, 
orthoclase, albite, &c., are well known to occur changed into a car- 
bonate (calcite, 
Desceiptioi^ oe Figuees in Plate XIY. (Science.) 
Fig. 1. — Coast section, about one mile in length, on the east side of Loch Slappin, 
Isle of Skye. 
Fig. 2. — Layers of serpentine, &c. ("chamber casts" oi'-'' Eozoon Canadense'^), with 
calcitic spaces ("intermediate skeleton") between them, curling round siliceous 
nuclei : natural size, as seen in a large block of ophite, from near the Manse, 
Kilbride, in Skye. 
Fig. 3. — Layers of malacolite or white pyroxene, separated by calcitic layers : na- 
tural size, from a weathered specimen of ophite, near Torrin, Skye. 
Fig. 4. — Layers of a dark-green mineral ( ? loganite), separated by dolomitic layers : 
natural size, from weathered ophite, near Torrin, Skye. 
Fig. 5. — Cylindrical parallel aciculi (*' nummuline layer") on the sectional edge of 
a piece of serpentine : highly magnified. In ophite, from Strath, Skye. 
Fig. 6. — Simple and branching configurations ("canal system") composed of ser- 
pentine, and imbedded in calcitic layers ("intermediate skeleton") of ophite, 
from Strath, Skye. Highly magnified. 
Fig 7. — Configurations composed of malacolite, and imbedded in calcitic layers of 
ophite, from Strath, Skye. Highly magnified. 
* In some varieties of the amphibole group, the basic constituents solely consist 
of lime and magnesia. Malacolite, according to Dana, is composed of — Sil., 55-7 ; 
lime, 25*8; mag., 18'o ; and tremolite is formed of the same salts, but inversely 
proportioned. 
t See "Dana," pp. 272, 344, 361,678. 
