chemical analyses of igneous rocks

492 Pages·2010·18.17 MB·English

Se 'es ' er°SraPly an(l Mineralogy, 23
Professional Paper No. 14
E, Chemistry and Physics, 37
DEPARTMENT OF THE INTERIOR
UNITED STATES GEOLOGICAL SURVEY
CHARLES I). WALCOTT, DIEECTOE
CHEMICAL ANALYSES OF IGNEOUS ROCKS
PUBLISHED FROM 1884 TO 1900
WITH A
CRITICAL DISCUSSION OF THE CHARACTER AND USE OF ANALYSES
HENRY STEPHENS WASHINGTON
W A S III N G T O N
GOVERN M K N T l> K I N T I N G OFFICE
11) 0 3
CON TENTS
I ettei of tnnsmittil 5
Prelat e 7
Introduction _ n
The cVuracter o£ lock -uialvses 13-
General considerations lo.
Kepresentatneness K>
Character of the rock mass It,
Amount ot material IS
Microscopical examination 1<)
Accura< y 1Q
Possible eirors _>0
Coiiipletenes« 2 >
Mam constituents 24
Minor constituents 25
Eating ot anal\ '-cs 28
Accurac\ 2')
Internxl evidence ^0
Agre emcnt \\ ith the mode 30
Summation -j^
Fxternal e\idcnce 3g
Methods ^g
Indirect e\ idence 3B
Completeness =57
Rating adopted in the tables 33
Discussion ol the tables 4
Di \iaion into parts 4^
Part I 44.
Part II 4->
Basis ot arrangement ol aualj =es 4f(
4ttempted use ol current pptrogriphu sj^tem 4g
Adoption ot the quantitative sjstem 47
Quantit iti\e classification of igneous rocks 47
Constiuction of the sjstem 47
Nomenclature of the system 48
Comparison of old and new nomenclatures 49
4 CONTENTS.
Discussion ot the tables Continued
Quantitative classification of igneous locks Continued Page
Tabular exhibit of divisions and names of quantitative system (5 tables).--...---..... 53
Keasons for anangement according to the quantitative classification .................. 59
Distribution of rocks by new system................................................ 61
Comment on facts expressed by tables.............................................. 62
Various features of the tables .-............................................"... ........ 64
Geographical arrangement.............................. ..................... 64
Numbering ol analyses ........................................................ 65
Eating of analyses .................. ......................................... 65
Results ot rating analyses............................................... ..... 65
Constituents.................................. ............................... 67
Specific gravity ........ ...................................................... 68
Norm ........................................................................ 68
Correspondence of norm and mode.......... .................................. 69
Locality...................................................................... 69
Analyst...................................................................... 70
Reference --.....-----.-.-...............-......-......--.-...-............... 70
Author's! name..-.-.--.......... ............................................ 71
Remarks ..................................................................... 71
Correlation of the qualitative and the quantitative systems................................... 72
From the qualitative point ot view ..................................................... 73
From the quantitative point of view -......--...,.--......--......--..-...-...-.--...... 76
Meteorites......-.....-....-..-.......-......-..........-....-..-...--.-...--...-.--.- 81
Calculation oi center points................................................................ 81
Intioductory ..... .....-...-.--........-...-..-......-----.-.--......--.-..--.-...... 81
Peisalane............................................................................. 84
Perfemane..............-...-.-................--.....--.-...---.-.-.--...-.-.-.....-. 88
Distribution ot magmas and the average rock ............................................... 100
Introductory ..-........-.-.-..-,.......-......-......-......-.-..-..-..-....- ....... 100
The distribution of magmas. -.-......-.....-....-..-.-....-...-..-.--.-..---...----.... 102
The average lock ..................................................................... 106
First method ..................................................................... ' 106
Second method ................................................................... 109
List of abbieviations ..............--.............................-------.--.....--.....-.. 116
Collection ot rock analyses............................ -......-......---.--.--....----..-.. 1-1
Parti............ ................................................................... 121
Part II............................................................................... 371
Glossary ..............................................--......---.....---.-.--.---..--.-. 475
Prefatory note to indexes....-......-......-..-.....--.....---.--.--.---.-.----.-----.----- 481
Index to text............................................................................. 483
Index to new rock names in Part I.........-.-.....-......-.--...--.....-...-.------------- 486
Index to old rock names m Parts T and II........ ...... ........-.-------.-- .-....----... 489
Index to localities in Parts I and II................ .........---------.-.-----.------.----- 493
LETTER OF TIUNSMITTAT,
DEPARTMENT OK THE INTERIOR,
UNITED STATES GEOLOGICAL SURVEY,
ITWm^/Aw, ]). ('., March 20, 1903.
SIR: I have the honor to transmit to you a manuscript entitled "Chemical
Analyses of Igneous Rocks published from 1884 to 1900, with a critical discussion
of the eharae.ter and use of analyses,'' by Henry Stephens Washington, and to recom
mend that it be published by the Survey as a Professional Paper. This work is pri
marily a compilation of chemical analyses, and is especially valuable to petrographers
and chemists, for it places in one volume material gathered from a great many scat
tered source's. The critical discussion of the value and use of rock analyses, with
comments upon methods of analysis and a review of the bearing of this mass of
material upon rock classification, is also of much importance to both petrographers
and chemists. The arrangement of the analyses according to the quantitative system
for the classification of igneous rocks permits one to compare readily any new
analysis with many others of closely allied rocks. A work of this kind is necessarily
very expensive when published by a commercial house, and if so issued would be
beyond the reach of many who would desire to use it. It is particularly appropriate
that the Survey should publish this work, because a very large proportion of the,
rock analyses here included have been made in the laboratory of the United States
Geological Survey, upon material which is preserved in its petrographic, reference
collection. The use of that collection will be greatly facilitated by this work.
Very respectfully.
WHITMAN CROSS,
G-I'O! fig !#t in Chary e Section of Petrology.
Hon. CHARLES I). WAL.COTT,
Director IJ. S. G-eoloyhul
PREFACE.
The collection of chemical analyses of igneous rocks here presented was made
during a period covering several years, for purposes of ready reference in certain
lines of investigation. In view of the gieat value of that standard work of reference,
Roth's Tabellen, and of the fact that no such collection of rock analyses has appeared
since the last installment of these in 1884," it was thought that an extension and
completion of these along the lines of Roth's work, so as to bring them down to the
present day, would be welcome to petrographers. This seemed to be the more
advisable because the years that have elapsed since 1883 have witnessed a very
marked increase in the number, as well as a great improvement in the quality, of
chemical analyses of rocks. These years have also shown a steady increase in the
importance of chemical analyses as applied to the discussion of petrological problems,
and a growing tendency to use them as bases for various systems of classification
which have been proposed.
The classificatory work on which I have been engaged in collaboration with
Cross, Iddings, and Pirsson, the results of which have recently appeared,6 was
also a powerful incentive to the formation of the present collection. As has been
stated by us, this collection has been appealed to whenever possible, as a test of our
proposed system of classification, and has also formed to a large extent the basis of
the roots of the magmatic names suggested.
The years embraced in the present collection are those from 1884, that of the
publication of the last of Roth's Tabellen, to 1900, both inclusive. The former was
selected as a starting point because Roth collected nearly all the analyses which
appeared in 1883; yet some of those which he overlooked are included in this col
lection. The year 1900 seemed to be appropriate as the other time limit, partly for
the reason that it was the closing year of the last century, and partly because in that
year appeared Bulletin 168 of the United States Geological Survey, which is the latest
publication embracing all the analyses of rocks made by the chemists of that organi
zation. At the same time, since the collection is to a large extent illustrative of our
oRoth, J , Beitrage zur Petrographie der plutomschen Gestemo Sitzungsber K Preuss Akad Wiss, Berlin, 1884
ft Journal oi Geology, Vol X, 1902, p 555, also, Quantitative Classification of Igneous Rocks, Chicago, 1903
8 PREFACE.
proposed S3'srem of classification and nomenclature, some analyses published prior to
1884 or subsequent to 1900 that are of especial interest or importance have been
included, as illustrations of the classificatory divisions, or as forming the bases of the
magmatic names.
The endeavor has been made to present all analyses of igneous rocks, good, bad,
and indifferent, that have been published within the time limits selected. For this
purpose I have examined the most complete accessible files of all known geological
survey publications, as well as those of geological and other scientific societies, the
various geological journals, inaugural dissertations, etc.
It is of course impossible that all analyses published during the time given should
have been collected. Some of the less well-known publications of scientific societies
are inaccessible in this country, and, indeed, at the tinie the material was collected
(1900 and 1901) the later publications of some of the surveys and societies wore, for
obvious reasons, not to be had here. But it is believed that the collection is fairly
complete, and that it contains at any rate a record of much of the most useful and
noteworthy chemical work of the seventeen years which it represents.
It is hoped that occasional appendixes will be published later, in which, if possi
ble, inanj7 of the anatyses here overlooked will appear. For this purpose I shall
esteem it a favor to have my atteation called to omissions, and shall be under great
obligations to those who will be kind enough to send separates of publications which
have, been overlooked in the present collection or which may appear subsequently in
journals that are accessible here with difficulty or not at all. It is to be regretted
that the current reviews publish so few of the analyses contained in the papers
reviewed, for these analyses are often of the greatest interest. In the present trend
of petrology they are often of much more importance than the microscopical details,
which are frequently cited at length.
Although great care has been taken to guard against errors in collecting the
analyses, preparing- the manuscript, and reading the proof, mistakes arc almost
unavoidable in dealing with the mass of figures represented. I can not venture to
hope that they have been entirely eliminated, and can only express my regrets at
their existence, and trust that my attention will be called to them a favor which will
be very highly appreciated.
The collection is strictly confined to analyses'of igneous rocks. It was at one
time intended to include also those of rnetamorphic rocks, but the delay which this
plan woiild have involved seemed finally to render it inadvisable, though a fairly
complete collection of such analyses had also been made in conjunction with those
here given. Sedimentary rocks of all kinds have also been omitted, though analyses
of volcanic tuffs are included. Analyses of serpentines are likewise excluded, since
they are due either to the decomposition of igneous rocks, so that, as explained
PREFACE. 9
elsewhere, their analyses would fall under the ban imposed on such altered material,
or are derived from either metamorphics or mineral masses, and hence fall outside
the scope of the present collection.
It was hoped for a time that analyses of meteorites could be given; but owing to
the fact that no adequate collection of the analyses of these bodies has yet been made,
this would have involved a search through the voluminous and widely scattered lit
erature published concerning theiii since the commencement of their study. Such
a proceeding would have postponed indefinitely the appearance of this work, and
therefore, as well as in view of the fact that they form the subject of special studj7,
the project was abandoned. I am informed, furthermore, that such a collection is
already being- undertaken by another, so that it is to be hoped that this serious lacuna
will shortly be filled.
It may seem to many petrographers who are acquainted with the chemical analy
sis of rocks that certain portions of this subject have been gone into with unnecessary
detail, or that many truths are stated which arc obvious to any one conversant with
the subject. That this is true to a large extent is admitted, but it must be remem
bered that the greater part of the text which is devoted to this subject has been
written with the nonanalytical reader in mind, to whom much of what is here given
will undoubtedly prove novel. As will be evident from a perusal of the text and
from a study of the analyses here presented, there are far too many petrographers
to whom the principles and methods of chemical analysis are as a sealed book, and in
their case I can only feel that if I have erred it has been on the side of too little
explicitncss or detail.
The new terms and names used are those proposed in connection with the recently
published quantitative classification, and their meanings will be found in the glossary
given on pages 479-483. No apology is offered for their introduction, since in many
cases they are the only terms available to express the ideas which it is desired to
conve}7, at least without the use of much longer or circumlocutory phrases, and it
was desired as well to take this opportunity of making them more familiar to
petrographers.
The progress of the work has been greatly facilitated by the kindness of many
friends, to whom it is a pleasure to express obligations. I am especially indebted to.
the officials of the libraries of Yale and Columbia universities and of the United
States Geological Survey, who courteously afforded me the fullest facilities in the
examination of serial and other publications. Without their assistance this collection
could not have been made satisfactorily complete.
I am also indebted to several friends, among whom I may mention especially
Profs. J. F. Kemp and J. B. Harrisoii, for several unpublished analyses, which they
kindly allowed me to insert in the tables. To my friends Dr. Cross, Professor
10 PREFACE.
Iddings, Professor Pirsson, and Dr. Hillebrand I am grateful for many valuable sug
gestions and criticisms. Nearly the whole of the manuscript of the text has been
.submitted to my-colleagues in the new classification, so that the views here expressed
may be regarded, in general, as having their indorsement, and as expressing the
ideas of all four.
Last, but by no means least, I must express my sense of deep obligation to the
Hon. C. D. Walcott for his kindness in allowing the work to appear as a Survey pub
lication. It is gratifying to feel that this hospitality is in part repaid by the incon
testable evidence the present volume affords of the preeminent place in rock analysis
that is held by the organization of which he is the Director.
Finally, I must express my regret at the delay in the appearance of the work,
which is published more than two years after the limiting date of the collection. 1
can only plead in extenuation the pressure of other work, especially that in connec
tion with the new system of classification, and trust that the time which has elapsed
has but added to whatever worth the volume may possess.
CHEMICAL ANALYSES OF IGNEOUS ROCKS.
By H. S. WASHINGTON.
INTRODUCTION.
In the first two or three decades of the last century, when the study of rocks as
such was being differentiated from that of minerals and of rock terranes that is,
when the science of petrogaphy was in its infancy little attention was paid to their
chemical features. It is true that a number had been analyzed, but these were for
the most part rocks that were of such a character as to lead the investigator of those
early days to consider them as minerals, as was the case with the first described
Ihcrzolite and wehrlite. In contradistinction to the individually well-defined rnin- '
erals, rocks were regarded as merely aggregates of minerals, in presumably fortui
tous combinations, and lacking that definiteness or constancy of composition in one
mass or in different masses which would justify their chemical study as a whole.
As, however, they became more and more the subjects of special research, beginning
with the earliest investigations of Cordier,a a knowledge of their chemical composi
tion assumed gradually increasing interest. The great importance of this side of
the study of rocks was first clearly recognized by Abich,s who pointed out, as early
as 1841, the, necessity of a knowledge of their chemical composition for the solution
of such problems as their origin, mode of formation, and connection with the
interior of the earth, as well as the value of a comparison of their analyses as a
proper basis for their classification and nomenclature. To him, therefore, is due the
credit, of introducing the chemical composition of rocks as a basis for their classifi
cation; though the good influence of this suggestion for their right understanding
was largely nullified by the coincident use of the feldspars alone as one of the main
factors of classification," an idea which has had a deplorably retarding influence on
the development of systematic petrography for many 3rears, and which, even at the
present day, holds many systematists firmly in its grasp.
a Of. Cross, Whitman, Jour. Geol., Vol. V, 1002, p. 352.
6 Abich, H.. Natur dor Vulkanische Bildungen, Braunschweig, 1841, p. v.
< Cross, Whitman, loc. cit., p. 362.
11
12 CHEMICAL ANALYSES OF IGNEOUS KOCKS.
For about thirty years after Abich's publication chemical analyses occupied a-
prominent position in petrographical discussions, being employed largely for the
purpose of determining the mineral composition of rocks. Abich, in the work just
cited, had adopted as a means to this end the ratio of the oxygen of the bases to that
of the silica, and was thus enabled to calculate approximately their mineral composi
tion, as Raimuelsberg and others had also done.
A modification of this method, known as the "Oxygen-ratio" (Sauerstoffquo-
tient), was introduced by Bischoff," and was long employed for the correlation of
rock analyses and for the investigation of the question whether the various oxides
were present in rocks in stoichiometric proportions or not. This ratio is obtained,
for any given rock, by dividing the amount of the oxygen in all the bases bv that
present in the silica, and was supposed to be characteristic of different broad groups.
This supposition was eventually found to be unwarranted, as rocks of very diverse
chemical or mineralogical characters were shown to have the same oxygen ratio. It
is noteworthy that, although he himself pointed out this and other grave objections
to the use of this ratio,* Roth gives it in connection with the separate analyses in all
his tables, even in the last one, published in 18S4. He explains this by saying0 that
it is done, "only in the absence of a better means of comparison, as well as to make
it possible to compare the older and newer analyses."
It was also shown by Roth and others that rocks could not be referred to simple
chemical formulae; in other words, that the oxides were not present in stoichiometric
proportions. This, indeed, is one of the most important of the results arrived at by
Koth from a study of the analyses collected by him, and first published in 1861.
Shortly after Bischoff's suggestion of an oxygen ratio there appeared <? Bunsen's
well-known hypothesis of the formation of igneous rocks by the mixture of two
supposed original magmas the normal traclrytic and the normal pyroxenic. For
the application or the discussion of this hypothesis, analyses were, of course, all-
important. Founded, as the hypothesis was, on limited and totally insufficient
data, 'it had to yield to the evidence furnished by the many analyses to which it
had given rise.
With the abandonment" of this view of the genesis of igneous rocks, and owing
to the coincident introduction of the microscope in the early seventies, analyses lost
much of their importance. Though they were still published, it is evident that they
were, as a rule, inserted perfunctorily in petrograpbical writings, in obedience to
custom, as ornamental embellishments. Little or no stress was laid on them, and the
chief efforts of the petrographer were devoted to the elucidation of the purely min
eralogical and textural characters of the rocks described.
aBischoS, G., Lehrb. Cheni. Geol., Vol. II, 1849, p. 631. rfBnnsen, K., Pogg. Ann., Vol. LXXX1II, 1851, p. 197.
6 Roth, J., Gesteins-Analysen, Berlin, 1861, p. x. e Cf. Zlrkel, Lehrbuch, Vol. I, 1893, pp. 658 et seq.
cBoth, J., Biiitr. Petrog. Pluton. Gcst., 1869, p. 87.