SALMON — RESEARCHES ON PSEUDOMORPHS. 
17 
circumstance whicli should surprise us, for kyanite is found especially 
in rocks whicli are very rich in mica ; moreover, the mica which 
penetrates it is completely identical with that of the mica-schist in 
which it is formed. It is, therefore, very plain that the mica and the 
kyanite Avere crystallized simultaneously, and at the same time as the 
rock which incloses them. 
The same remark applies to andalusite, to chiastolite, to staurolite, 
to hornblende, to augite, &c., which are often more or less penetrated 
by the micas. In the very numerous specimens I have examined, 
the various minerals were not pseudomorphosed ; they simply en- 
veloped the micas, which were identical with those of the rocks in 
which they were formed. 
The largely lamellar chlorite, which in chlorite-schist envelopes 
and penetrates, often in the most intimate manner, crystals of mag- 
netite, and which does not differ from that which constitates the 
chloritic schist itself, does not seem to me to result any the more from 
a pseudomorphism. 
I am inclined to believe that it will be necessary to make pretty 
numerous suppressions among the minerals which are regarded as 
pseudomorphic, and particularly among the silicates. The only 
pseudomorphic which should be retained are those which take the 
form of another, and which are, besides, susceptible of replacing it 
completely. It is, moreover, easy to understand that when minerals 
have ciystalHzed simultaneously, they were in a position to associate 
and'envelope themselves in easy proportion ; which, indeed, before long 
will become still more evident. 
27id, JUnvelojpment with Symmetrical Arrangement. — Envelopment 
is sometimes accompanied by symmetrical arrangement, and then it 
is necessary again to distinguish many cases. 
Symmetrical arrangement is observed, in its mdimentary state, 
whenever the two minerals are grouped in respect to each other with 
a certain symmetry. This, for example, is what seems to occur in 
the galena of Is eudorf, in the Harz, which forms a thick and more or 
less regular crust around calcite. According to Messrs. Scheerer 
and Blum, this galena is in very brilliant crystals, which attain the 
size of a nut, and present combinations of the octohedron, the cube, 
and the rhomboidal dodecahedron. It envelopes the calcite, and is 
also enveloped by it. Its thickness is often reduced to that of a 
sheet of paper. 
Garnet offers the same peculiarities at Arendal, at La Bergstrasse, 
and at Le Canigou ; for its crystals envelope calcite which is likewise 
crystallized, and the tliickness of their sides may become microscopic. 
Sometimes also a crystal of garnet envelopes pistacio-green epidote 
(pistazite), which in its turn envelopes the calcite. Moreover, 
garnet may similarly envelope felspar, quartz, hornblende, diallage, 
gypsum, &c. 
The idocrase of Christiansand, which has formed in the saccarhoid 
limestone, is in large crystals, which have only a few lines of thick- 
ness, and which also envelope the calcite. 
VOL. IV. c 
