20/40 SILICA proppant, also called sand or coarse sand, is produced from a very high quality Ordovician St. Peter Sandstone layer in our Clayton, IA quarry. Our line of silica proppants is made of a high-purity quartz sand that is highly spherical and crush resistant. Our 20/40 SILICA PROPPANT is produced for use by the oil & gas petroleum industry. Pattison 20/40 SILICA PROPPANT is used in safe and proven hydraulic stimulation processes used for over 70 years on in excess of 2 million oil and natural gas wells. Because shale plays hold vast amounts of oil and natural gas lack adequate pore space for these fluids to flow to a well, our proppants are effective in assisting to hold tiny cracks in the shale open so that these liquids and gases can flow to the well head.