90 Notice of the Address of T. Sterry Hunt. 
5. That he attributes an origin similar to that for serpentine 
and talc to beds of chlorite and hornblende :—notwithstanding — 
the fact that chlorite schist and hornblende schist—the purest 
forms of any large beds of these minerals—are always more or 
less impure, and often graduate into clay slate on one side, and 
mica schist on the other; and, that these schists are thus so 
involved with others, that if one is derived from ordinary sedi- 
mentary beds, all must be. 
6. That he devotes some pages to a “ theory of envelopment” 
as a method of accounting for the silicate pseudomorphs 1 
ferred to—beginning a paragraph with the sentence: 
the greater number of cases on which this general 
ar 
theory of pseudomorphism by a slow process of alteration in 
minerals has been based, are, as I shall endeavor to show, examples 
of the phenomenon of mineral envelopment, so well studied by 
Delesse in his essay on Pseudomorphs :” 
and then gives a long list of admitted pseudomorphs, including | q 
in it nearly all kinds go recognized by~other authors, and - 4 
that affect the question discussed by Prof. Hunt; serpentine — 
occurring in the list as forming pseudomorphs after chrysolite, 
hornblende, garnet ; steatite after pyroxene, hornblende, epieom 
is 
pentine, etc. 
= 
nA 
