PUMICE

Pumice is an extrusive igneous volcanic rock formed through the cooling of air-pocketed lava, which results in a highly porous, low-density rock. The low density allows some pumice to float on water. Large pumice rafts, consisting in some instances of thousands of individual pieces of pumice clumped together, are a unique geologic phenomenon and have been documented to be as long as 30 km and to have drifted for several years in oceanic waters. Pumicite is defined as grains, flakes, threads and (or) shards of volcanic glass finer than 4 mm in diameter. Pumicite and volcanic ash are descriptive terms that are often used interchangeably. The porous, lightweight properties of pumice are well suited for its main use as an aggregate in lightweight building blocks and assorted building products. Production and price According to U.S. Geological Survey publications, mine production of pumice in the United States during 2022 was estimated to be 510 kt, which was essentially unchanged from that of 2021. The unit value of pumice was estimated to be $50/t in 2022, 9 percent higher than that of 2021. Production occurred at 10 operations in California, Idaho, Kansas, New Mexico and Oregon. According to the U.S. Census Bureau, U.S. pumice exports totaled about 13.9 kt. Imports were higher at 1.03 Mt. World resources of pumice are adequate for the foreseeable future. However, transportation costs may encourage development of deposits closer to markets. Total world production of pumice was estimated to be 15 Mt in 2022. Pumice is used more extensively as a building material outside the United States, which explains the large global production of pumice relative to that of the United States. The top world producers in 2022 were, in descending order of production, Turkey (5.4 Mt), Uganda (1.1 Mt), Greece (960 kt), Algeria (900 kt), Jordan (900 kt) and Ecuador (800 kt). Processing and consumption Pumice is usually extracted by simple openpit methods using rippers, bulldozers and front-end loaders. Processing typically is limited to drying, crushing and screening, although some abrasive grades may require fine grinding and classification. Lightweight pumice building blocks, the primary use for pumice, may be sawn into a variety of shapes and sizes. In 2022, other major applications included abrasives and horticulture (including landscaping). Minor applications include the use of pumice as an absorbent, as a concrete aggregate and admixture, as a filter aid, and as a traction enhancer for tires. A small percentage of pumice was used in abrasive-type products, including pencil erasers, polishing agents for circuit boards and television monitors, tooth-filing mechanisms for chinchillas, exfoliants in cosmetics and the removal of henna tattoos, and a variety of heavyduty hand cleaners. Imports were primarily used as raw material for building block (for example, cinderblock) and other lightweight aggregate applications. Several substitutes exist for pumice in agriculture, in horticulture, as an aggregate, as a concrete additive, and in other end products. Outlook Although pumice and pumicite are plentiful in the western United States, legal challenges and public land designations could limit access to known deposits. Pumice and pumicite production is sensitive to mining and transportation costs. An increase in fuel prices would likely lead to increases in production expenditures; imports and competing materials could become attractive substitutes for domestic products.

PUMICE

Authored by:
R.D. Crangle Jr

To view the past issues of the UCA magazine you must be a member of SME/UCA.

Gold retains key reserve status despite surging bond yields, central bankers say

China demands copper supply commitments for Anglo Teck merger approval, sources say

Leaders in mining excellence honored by NMA, federal agencies

Gold retains key reserve status despite surging bond yields, central bankers say

China demands copper supply commitments for Anglo Teck merger approval, sources say

Leaders in mining excellence honored by NMA, federal agencies

To view the past issues of the UCA magazine you must be a member of SME/UCA.

POTASH

RARE EARTH ELEMENTS

Related Articles

How GeologicAI uses high-resolution data to reduce uncertainty in mining

AI-ready digital twin for mineral processing plants: Maximizing copper production with dynamic water management

Roundtable discussion on mine finance

Bubbles and particles for fun and profit

Gold retains key reserve status despite surging bond yields, central bankers say

China demands copper supply commitments for Anglo Teck merger approval, sources say

Leaders in mining excellence honored by NMA, federal agencies

Gold retains key reserve status despite surging bond yields, central bankers say

China demands copper supply commitments for Anglo Teck merger approval, sources say

Leaders in mining excellence honored by NMA, federal agencies

Use Single Sign On