about pumice site
page title: mining and refining processes for pumice

Mining pumice and further refining it for use in the industrial and product manufacturing marketplaces is a benign process. It’s not unlike a gravel pit operation to produce the mine grades, with the refining process requiring more carefully controlled crushing, screening, grade-sorting and blending, and final packaging—no chemical treatments, no troublesome byproducts.

The Mining Process

Mining pumice from Wright Creek area deposit in southeast Idaho is a straight-forward process. The overburden (soil on top) is removed and stockpiled for later replacement during reclamation. Once exposed, the pumice is ripped and scraped from the deposit with a dozer blade, pushed into piles and conveyed to the preliminary crusher. The rough-crushed stones are then dropped through a set of configurable screens to produce various mine grades. Mine grades range from one-inch stones to powdery fines, with various blended grades made up of these particle size ranges. These mine grades are characterized by a more jagged-edge appearance and moisture-adhered fines clinging to the larger stones.

Pumice is sold in mine grades by the ton, and shipped directly from the mine.

Refining Pumice to Processed Grades

Hess offers scores of refined grades and grade blends to meet a variety of tight-tolerance industrial processes and product component needs. Mine grades are trucked to the Hess refining plants nearby, and run through one of two custom-designed processing plants. Here, the mine grades are further refined: dried, crushed, and screen-separated into various grades and grade blends. For some specialized grades, additional processing removes the trace igneous non-pumice “heavies” (like obsidian) found in the deposit.01

The refined grades are continuously spec-checked using an combination of in-line monitoring and lab testing to assure each grade meets published specification.

Packaged for Market

Refined grades are available in a number of packaged configurations, depending on customer preference. Valved paper production bags, ranging from 35 to 50 lbs, are palleted, wrapped, and shipped by truck, rail, or ocean container. Other packaging options include small canisters, resealable pouches, paper barrels, and super sacks.

The refined grades are also bulk shipped, with the larger grades poured into hopper-style rail cars or tractor trailers, and the powdered grades pumped into specialized pneumatic trailers or rail cars.

Logistics: Getting Pumice to Market

Using standardized pallet-shipped goods processes (with the pumice packaged either in production bags, barrels, or super sacks), and common bulk-shipper vessels, Hess moves pumice to the world market via truck, rail, and shipping container. They also provide the critical logistical expertise to navigate always-complex shipping networks to successfully shepherd pumice from their loading docks to the customer’s receiving docks. Pumice can also be shipped directly to a job site, as necessary.

Hess Pumice Products

Hess Pumice Products is a family-owned and operated pumice mining and refining company that has worked their nature-blessed pumice deposit since 1959.02 Hess has a well-earned reputation for delivering their superior brand of pumice on spec and on time. Their engineering and processing chops assure they can develop grade blends for any need. Their deep expertise in pumice-product innovation and development allows them to work closely with those exploring a pumice-component solution to a new or existing product or process.03


Mining and refining pumice is a low-impact, straight-forward process. The foamed-stone form factor that makes pumice so useful is forged from a volcanic event: no fuel-fired fiery furnace processing04 necessary. A mild drying process is necessary to allow mine-grade feedstock to flow through the plants—the refining crushers and screening stacks and separators—and into storage bins or through packaging equipment. No chemicals are used in the refinement process. No toxic by-products are generated. Pumice is found in abundance planet-wide, and the Wright Creek area Hess deposit in southeast Idaho has a confirmed yield of millions of tons.