90% igneous rocks, 5% metamorphic and 5% sedimentary rocks of those pea sized or greater. About 4% of the sample is less than 5 mm. in diameter down to sand, silt and earthy, colloidal matter
Cite the IMLGS database as: Curators of Marine and Lacustrine Geological Samples Consortium. The Index to Marine and Lacustrine Geological Samples (IMLGS). National Geophysical Data Center, NOAA. doi:10.7289/V5H41PB8 [date of access].