Lithology Classification

Thu May 4 17:05:06 2000

A comment by Stephen M. Richard about

Science language for geologic-map databases

As an exercise in deciding what lithology terms needed to be defined for our
geologic map database here at the AZGS, I worked with Tim Orr here to
compile the lithology terms used in a number of published databases. These
included the IUGS igneous rock chemistry database (IGBA1), the lithology
classification 6 list by Johnson (1999), the lithology words included in the
Model 4.3 (Johnson et al. 1999) document, the Petros database, my personal
samples database, and USGS DD14 (geochronology) database. We went through
the terms (7837, with duplicates removed), edited out the ones that we
deemed not useful lithologic names (e.g. alkalic rock, alluvial fan, altered
latite-phonolite, 1401 terms all told), and then using the AGI Glossary of
Geology (3rd  edition) translated abandoned or not recommended usage to
recommended usage terms. We ended up with a list of 251 terms. These are 67
lithology terms that appeared 10 times or more, and account for 92% of the

LithClass, Count
andesite, 463
granite, 311
gabbro, 265
rhyolite, 262
dacite, 241
syenite, 220
diabase, 219
trachyte, 173
granodiorite, 169
tuff, 162
quartz monzonite, 130
phonolite, 114
diorite, 101
monzonite, 90
rhyodacite, 85
quartz diorite, 82
nepheline syenite, 79
trachyandesite, 71
lamprophyre, 69
pumice, 65
cumulate, 57
latite, 55
glass, 53
obsidian, 51
pyroxenite, 48
trachybasalt, 47
basanite, 46
peridotite, 45
norite, 40
nephelinite, 40
aplite, 40
porphyry, 37
granophyre, 37
ash, 31
shonkinite, 29
quartz syenite, 28
tonalite, 28
tephrite, 25
carbonatite, 25
gneiss, 23
mugearite, 23
quartz porphyry, 23
pegmatite, 22
felsite, 22
shoshonite, 21
quartz trachyte, 20
ijolite, 19
schist, 18
dunite, 18
basanitoid, 18
komatiite, 17
theralite, 15
clinopyroxenite, 15
alaskite, 14
pyroclastic rock, 14
anorthosite, 13
agglomerate, 13
absarokite, 12
lherzolite, 11
hawaiite, 11
vitrophyre, 11
essexite, 11
leucitite, 11
ignimbrite, 11
trondhjemite, 10

We have produced a draft lithology classification table that is available for
review at

This is a tab-delimited text file; the field names are in the first row. The
classification follows the conceptual model put forward in Richard [1999]
Not all of the fields have values yet—null means not entered. This is a work
in progress. The table includes 384 lithologic names, culled from the
above-described compilation, the AGI Glossary of geology, and the SCAMP word
lists (Matti et al ) The
definitions are from the AGI glossary. It has not been reviewed in any
fashion as yet, but I suggest it might provide a good starting point for
definition of lithology names.

Context of this discussion

This page is part of a discussion of Science language for geologic-map databases:

Further discussion of Lithology Classification (this page):