| Clinoptilolite | |
|---|---|
 Clinoptilolite-Na | |
| General | |
| Category | Tectosilicate minerals |
| Group | Zeolite group |
| Formula | (Na,K,Ca) 2–3Al 3(Al,Si) 2Si 13O 36•12H 2O |
| IMA symbol | Cpt[1] |
| Strunz classification | 9.GE. |
| Identification | |
| Mohs scale hardness | 3.5–4 |
| Luster | Vitreous |
| References | [2][3][4] |
Clinoptilolite is a naturalzeolite composed of a microporous arrangement of silica and alumina tetrahedra. It has the complex formula(Na,K,Ca)
2–3Al
3(Al,Si)
2Si
13O
36•12H
2O. It forms as white, green to reddish tabularmonoclinictectosilicate crystals with aMohs hardness of 3.5 to 4 and aspecific gravity of 2.1 to 2.2. It commonly occurs as adevitrification product ofvolcanic glass shards intuff and as vesicle fillings inbasalts,andesites andrhyolites. It was described in 1969 from an occurrence in the Barstow Formation,San Bernardino County,California. Sodium levels in clinoptilolite are generally higher than potassium levels, as is the case with the San Bernardino Barstow Formation, but there are sources that are potassium-rich and have minimal sodium.[5]
It forms a series withheulandite:
Use of clinoptilolite in industry and academia focuses on itsion exchange properties having a strong exchange affinity forammonium (NH4+). A typical example of this is in its use as anenzyme-basedurea sensor.[6]
The name is derived from the Greek wordsklino (κλίνω; "oblique"),ptylon (φτερών; "feather"), andlithos (λίθος; "stone").
Clinoptilolite has many applications due to its effect as amolecular sieve, among others as an additive for building materials, asaggregate in horticulture, as an additive to cattle feed, as an additive in household products, as a desiccant, and in environmental technology.
Clinoptilolite was used on a large scale in thenuclear disaster of Chernobyl. There, the mineral was used on the one hand as anion exchanger in cleaning plants to treat radioactively contaminated wastewater. On the other hand, it was added to cattle feed in order to bind and eliminate radioactive cations such as137cesium as an ion exchanger in the digestive tract.[7]
Clinoptilolite is marketed within the EU asmedical product and is associated with scientifically unproven healing effects. It is not approved as afood supplement for human use due to theNovel Food Regulation. In Germany, it was therefore registered in December 2011 by theFederal Office of Consumer Protection and Food Safety under the rapid alert number "2011/1849" as an unauthorized novel food ingredient in food supplements.[8]
Clinoptinolite of sedimentary origin may be used as a "technological" additive in animal feed. It then has the function of binder. The European Commission authorized clinoptinolite in animal nutrition for all animal species in 2013.[9][10] Only clinoptinolite of sedimentary origin is allowed.
10. Kautsky, Mark. June 1984.Sorption of Cesium and Strontium by Arid Region Desert Soil. A thesis submitted in partial fulfillment of the requirements for the degree of Master of Science, Mackay School of Mines, University of Nevada, Reno.