vermiculite is a 2:1 clay meaning it has two tetrahedral sheets for every one octahedral sheet. it is a limited-expansion clay with a medium shrink–swell capacity. vermiculite has a high cation-exchange capacity (cec) at 100–150 meq/100 g.
raymond j. williams-jones a. e. & clark j. r. (2005). mineralization associated with scale and altered rock and pipe fragments from the berlin geothermal field el salvador; implications for metal transport in natural systems. journal of volcanology and geothermal research 145(1) 81-96. enoree vermiculite mining district
the largest vermiculite mining operation in the world is located in the phalabowra (also sometimes spelled palabora) district of the republic of south africa. other countries producing significant amounts of vermiculite include the united states china russia brazil japan zimbabwe and australia.
vermiculite is a clay mineral group with the general chemical composition (mgfeal) 3 (alsi) 4 o 10) (oh) 2 ·4(h 2 o). often occurring as an alteration product of biotite mica or chlorite in the near-surface zone of weathering vermiculite is typically found associated with ultramafic rock types such as peridotite and pyroxenite that have been previously altered by intrusions of granite
palabora america ltd. is the usa sales subsidiary of palabora mining company (pmc). pmc produces copper as a primary product together with by-products including magnetite nickel sulphate uranium anode slimes and sulphuric acid. industrial minerals production produces vermiculite. pmc is south africa's largest producer of refined copper.
vermiculite is mined using open cast mining techniques where the ore is separated from other minerals and then screened or classified into several basic particle sizes. every care is taken in mining operations to minimize the impact on the environment and to SevenTrust land to its natural condition when mining ends.