2 ANALYSES OF ROCKS AND MINERALS, 1880-1908. 
present only five are connected with the Survey. Other officers of 
the Survey have been occupied more or less with chemical questions, 
but the men named in this list were connected directly with the 
laboratory. Some work for the chemical division has also been done 
by chemists not regularly on the rolls of the Survey, but their analyses, 
with the exception of a single group to be noted later (see pp. 86-89), 
do not fall within the scope of this paper. 
Quite naturally, on account of the activity of the petrographers, a 
dominant feature of the laboratory work has been the analysis of 
rocks. These have been studied in great numbers and in the most 
thorough way. The results have appeared in widely scattered pub- 
lications, official reports, monographs, bulletins, American and foreign 
journals, and so on. The object of this bulletin is to bring together 
this valuable material, together with such bibliographic and petro- 
graphic data as seem to be necessary, in order to identify the speci- 
mens and to facilitate chemical discussion. Analyses of minerals 
have also been made in considerable numbers, and they are collected 
in the final section of this book. In some instances such analyses 
were made with direct reference to petrographic studies, and therefore 
are cited in connection with the rocks to which they belong. Meteor- 
ites, of which twenty-nine have been analyzed, are brought into the 
work on account of their petrographic relations, and the groups of 
clays and soils have been admitted because of the bearing of these 
substances on the study of slates and shales. The actual number 
of analyses given in the bulletin is as follows: 
Igneous and crystalline rocks@..............-....-.--2-.-------- 1,208 
Sandstones, cherts, and sinters........-....-.--.--------------- 81 
Carbonate roCkS:ss 24 sseeesssceseexeeneeeds tie ett veressee coves 273 
Slates and shaless.c.ccsevacvss wcassohensehadexceces 26a sales 63 
ClAVSy BOlIS; CIC ose vs Sine.ts oa Zacirscspleldg deus cae bea ease eeaes 130 
Meteorites, and separations from them..............-.--.------- 62 
MIDGPa lS taccccopiwennevdda. cs denne aetaieueaned ¢he.hedesanens 608 
2,420 
It may be observed that the classification thus indicated has not 
been rigorously followed. In a few instances the study of a sedi- 
mentary rock has been so related to that of its igneous neighbors that 
the analyses are best tabulated together; but these exceptional cases 
are few, and all are properly noted. The heading ‘‘Igneous and 
crystalline rocks” has been used in the broadest and most liberal way, 
and doubtless many of the analyses given under it might properly be 
otherwise classified. In such cases of uncertainty, convenience has 
furnished the rule to follow. 
Within each division of the analyses the classification chosen has 
been geographic. The petrographic grouping of the rocks would 
@ Including analyses of solublo or insolublefractions, ete. 
