USGS Lithology Patterns for QGIS as SVG with option to modify colors
These are derived from the USGS lithologic patterns previoulsly converted to Inkscape svg by the Univeristy of Otago. I pulled out the pattern section from the Inkscape template document and used a script to split the xml into individual svg patterns. I ran them through "SVG Cleaner" and opened in Inkscape to make sure the rotations and spacings were correct, and saved as plain svg. I then made a batch with the stroke color (or fill where required) as a parameter so they can be attributed to any color in QGIS.
Patterns with attributable color are in: /SED sedimentary /IGM igneous and metamorphic
Patterns with fixed color are in: /SED_fixedcolor sedimentary /IGM_fixedcolor igneous and metamorphic
There is also a QGIS workspace that shows all the patterns (and some blanks for future expansion). The symbols are linked via attribute names and the color can be assigned with the rgb() function.