| Saponite | |
|---|---|
 Saponite (light green) mixed with chamosite (dark green) and copper | |
| General | |
| Category | Phyllosilicates Smectite group |
| Formula | Ca0.25(Mg,Fe)3((Si,Al)4O10)(OH)2·n(H2O) |
| IMA symbol | Sap[1] |
| Strunz classification | 9.EC.45 |
| Crystal system | Monoclinic |
| Crystal class | Prismatic (2/m) (sameH-M symbol) |
| Space group | C2/m |
| Unit cell | a = 5.3 Å, b = 9.14 Å c = 16.9 Å; β = 97°; Z = 2 |
| Identification | |
| Color | White, yellow, red, green, blue |
| Crystal habit | Granular – Massive |
| Cleavage | {001} perfect |
| Tenacity | Brittle dry, plastic when hydrated |
| Mohs scale hardness | 1.5 |
| Luster | Greasy, dull |
| Streak | White |
| Diaphaneity | Translucent |
| Specific gravity | 2.24–2.30 |
| Optical properties | Biaxial (−) |
| Refractive index | nα = 1.479 – 1.490 nβ = 1.510 – 1.525 nγ = 1.511 – 1.527 |
| Birefringence | δ = 0.032 – 0.037 |
| Pleochroism | X = colorless, light yellow to green-brown; Y = Z = colorless, greenish brown to dark brown |
| 2V angle | Calculated: 20° to 26° |
| References | [2][3][4] |
Saponite is atrioctahedralmineral of thesmectite group. Its chemical formula isCa0.25(Mg,Fe)3((Si,Al)4O10)(OH)2·n(H2O).[3] It is soluble insulfuric acid. It was first described in 1840 bySvanberg. Varieties of saponite aregriffithite, bowlingite andsobotkite.
It is soft, massive, and plastic, and exists in veins and cavities inserpentinite andbasalt. The name is derived from theGreeksapo,soap. Other names include bowlingite; mountain soap;piotine;soapstone.
Saponite was first described in 1840 for an occurrence inLizard Point, Landewednack,Cornwall, England.[3] It occurs inhydrothermalveins, inbasalt vesicles,skarns,amphibolite andserpentinite. Associated minerals includeceladonite,chlorite,native copper,epidote,orthoclase,dolomite,calcite andquartz.[4]
Saponite is found inZąbkowice Śląskie inSilesia,Svärdsjö in Dalarna,Sweden and in Cornwall, UK. The soapstone of Cornwall is used in the porcelain factory. Saponite is also found in the "dark rims" of chondrules incarbonaceous chondrites and seen as a sign ofaqueous alteration.[5] Europe's largest primary diamond deposit,Lomonosov, in the Primorsky District ofArkhangelsk Oblast is an area of intensive accumulation and storage of saponite at the tailings.
The forecasted mass of saponite to be discharged into the tailings of diamond ore processing makes up millions of tons. Worryingly, when macro- and micro-components are found in non-hazardous concentrations, fewer efforts are put into the environmental management of the tailings, though technogenic sediments offer prospects for reuse and valorization beyond their traditional disposal. Saponite is a demonstrative example of the tailings constituent that is often left unfairly mistreated.
Electrochemical separation helps to obtain modified saponite-containing products with high smectite-group minerals concentrations, lower mineral particles size, more compact structure, and greater surface area. These characteristics open possibilities for the manufacture of high-quality ceramics and heavy-metal sorbents from saponite-containing products.[6] Furthermore, tail grinding occurs during the preparation of the raw material for ceramics; this waste reprocessing is of high importance for the use of clay pulp as a neutralizing agent, as fine particles are required for the reaction. Experiments on theHistosol deacidification with the alkaline clay slurry demonstrated that neutralization with the average pH level of 7.1 is reached at 30% of the pulp added and an experimental site with perennial grasses proved the efficacy of the technique. Moreover, the reclamation of disturbed lands is an integral part of the social and environmental responsibility of the mining company and this scenario addresses the community necessities at both local and regional levels.[7]
Synthetic saponites have defined chemical composition and reactive surface and serve as a substitute for zeolites. In contrast to the pores in zeolites, saponites have a larger layer spacing and can also be used as catalysts for larger organic molecules, e.g. in polymerization, isomerization and cracking.[8]
This article incorporates text available under theCC BY 4.0 license. This article incorporates text available under theCC BY 4.0 license.This article contains material from the U.S. Bureau of Mines Dictionary of Mining, Mineral, and Related Terms.
