102 J, D. Dana—Address of T. Sterry Hunt. 
But the most extraordinary feat is Mr. Hunt’s making out 
that the writer has virtually sustained the view of the metamor- 
phosis of granite or gneiss to limestone (p. 50), when, as I said 
before, it is an idea that never entered my head until the 
reading of Mr. Hunt's caricature of the subject. The proo 
which he gives is remarkable. In the first place, he says that 
my Mineralogy contains the fact that calcite is sometimes found 
pseudomorphous after quartz; and, in another place, the fact 
that calcite is found pseudomorphous after feldspar. Hence 
the conclusion, granite or gneiss to limestone. Q. KE. D. | 
Now, if the facts respecting the pseudomorphs were facts, 
it would still require great constructive powers to make out. 
rom the statements the conclusion that I ever held to the 
‘‘metamorphosis of granite or gneiss into limestone.” But, 
as to the facts: (1) The mineralogy does not mention any case 
of the pseudomorphism of calcite after quartz; and (2) the 
pseudomorphs of calcite after feldspar are spoken of as examples 
not of an alteration of the feldspar, but of its removal, and the 
substitution of calcite (4th edit., p. 249, and also 5th edit., 
p. 861). Now, by this substitution process, the above-mentioned 
metamorphosis would consist (supposing fact No. 1 to be a fact, 
and that mica crystals may be similarly changed to calcite, 
which Mr. Hunt omits to include) in a removal of all the 
materials of the granite by a process of solution, and the co- 
temporaneous or subsequent substitution of calcite ! 
All will admit that the use of facts and not-facts exhibited in 
_ the above charge is most extraordinary ; and can judge from it, 
* It is to be noted that serpentine pseudomorphs are sometimes pseudomorphs 
by substitution, as well as by alteration. Hither method is a result of “ epigenic” 
change, since it is produced by the action of external chemical agents. © 
