The ferrierite group of zeolite minerals (the FER structure) consists of four very similar species: ferrierite-Mg, ferrierite-Na, ferrierite-NH4 and ferrierite-K, based on the dominant cation in the A location. ferrierite-Mg and ferrierite-K are orthorhombic minerals and ferrierite-Na is monoclinic with highly variable cationic composition . Calcium and other ions are often also present. They are found in vitreous to pearly, often radiating, spherical aggregates of thin blade-shaped transparent to translucent crystals.
Ferrierite typically occurs as an alteration mineral in basaltic rocks and in tuffaceous sediments. In North America, it is found at Kamloops Lake, BC, Canada (the original type locality) and Leavitt Lake, California. Ferrierite was named for Canadian geologist and mining engineer Walter Frederick Ferrier (1865–1950).
Synthetic ferrierite
Synthetic ferrierites have even greater cation variability and have important uses as commercial filters and ion-exchange beds.
Ferrierite-H can be used as a catalyst in the chemical industry for the acid-catalyzed skeletal isomerization of n-butenes to isobutene, the raw material for production of methyl tert-butyl ether (MTBE).
The hydrophobic all-silica ferrierite (Si-FER) has very high selectivity in the separation of alcohol–water mixtures, due to the very restrictive shape and space constraints of the FER framework type. At high pressure, Si-FER can achieve the separation of an ethanol–water liquid mixture into supramolecular blocks of its components, namely, ethanol dimer wires and water tetramer squares.
Potential toxicity
Ferrierite is normally found as small plates or short prismatic crystals. However recent research found that in some locations, it grows as very thin needles or fibers. These fibrous varieties have been found in several localities, including northern Italy, Lovelock (Nevada, USA), and British Columbia (Canada).
Scientific research into the fibrous ferrierite’s habit has become very important because of its potential health risks that could be similar to minerals like asbestos and erionite, and is strongly linked to fiber shape and size. Long, thin, durable fibers can be inhaled deep into the lungs, where they may persist and irritate lung tissue. Surface studies also found that fibrous ferrierite can be chemically and physically similar to fibrous erionite, which is known to be highly carcinogenic. Researches recommended a precautionary approach when fibrous ferrierite is present until direct toxicology testing is completed.