REPORT OF THE DIRECTOR, I922 iy 
we can call them exchangites or replacites or metasomatites ; and 1f 
we do we shall be easily understood but there are not any such 
words in petrography. 
5 What term shall one use for an ash that has been completely 
silicified? I know that one form of it has been called novaculite, 
but not at all because of its origin. And on that very account the 
term would hardly serve for a rock that had a coarse structure. 
There simply is not any adequate term. This is not a rare thing. 
There is much more of this type of rock in the ground than there 
is of Jacupirangite, or of Luxullianite, or many others that could 
be named. 
6 What constitutes a quartzite? And why should not one dis- 
tinguish between a quartz rock that is still in its original, unmodified 
condition and one that has been indurated with silica; and, yet again, 
one that has been deformed and recrystallized? There are im- 
mense differences historically, and all types are very abundant 
indeed. 
In the field of katamorphism there are whole groups of products 
of immense importance to the practical or applied petrographer, 
for which there are no classification terms, although there are geo- 
logic terms descriptive of the major processes. 
7 For example, how shall one designate the average product of 
simple disintegration? Is it a disintegrationite? 
8 What shall one call the products of leaching? Shall we call 
them all laterites or leachites? Is laterite an extreme condition rep- 
resented less perfectly by all of the leachites? 
9 Or, again, what shall one call the product of simple oxidation? 
I know that “ gossan ” is an oxidation product from sulphides; but 
are they all to be called gossans? There ought to be a better name 
for the whole family of oxidationites. 
10 Or how shall one indicate in simple terms or by a suitable name 
that a rock is a carbonation product, when the original was not a 
carbonate rock at all? One has had little experience who has not 
seen such rocks and has wondered how to classify them. 
11. Hydration is one of the commonest processes active in the 
alteration of rocks. Serpentines are of such origin, derived from 
anhydrous silicate originals; but there is no name for the whole 
family of hydrationites. 
12 A sandstone in which carbonate occurs is usually called a cal- 
careous sandstone; but there is a great difference in meaning 
whether the carbonate is original with the rest of the rock or was 
