NEPHELINE
NEPHELINE Nepheline – Na3K(Al4Si4O16) – is a tectosilicate, an important feldspathoid, typical of silica-undersaturated rocks, both plutonic, hypabyssal and volcanic. It is also an industrial mineral with many different uses. Prismatic crystals of nepheline can reach 10 cm. Nepheline may contain Mg, Ca and H2O. There are two varieties. “Elaeolite” is a resinous gray, green […]
NONTRONITE
NONTRONITE Nontronite – Na0.3Fe2((Si,Al)4O10)(OH)2 · nH2O – is a phyllosilicate, a clay mineral that is part of the 17-member Smectite Group. It is quite common and has no economic importance. It can contain Mg, Ca and Ti and has two varieties (Al, Cr). Conclusive identification of nontronite by optical microscopy is not possible. Other analytical […]
NAGYÁGITE
NAGYÁGITE Nagyágite – [Pb3(Pb,Sb)3S6](Au,Te)3 – is a very rare sulfosalt, characteristic of Au-Te parageneses. It occurs in Au ores and constitutes Au and Te ore, but it is neither the only nor the main Au or Te ore mineral in the deposit. It is only very locally abundant. It may contain Bi, Ag, and Fe. […]
NOSEAN
NOSEAN Nosean – Na8(Al6Si6O24)SO4.H2O – is a tectosilicate, a feldspathoid from the Sodalite Group. It is a characteristic mineral of alkaline volcanic rocks and has no economic importance other than a mineral for collection. Powdered alkaline rocks, on the other hand, are used in the glass and ceramics industry as fluxes. Macroscopically, nosean can be […]
NATROLITE
NATROLITE Natrolite is a relatively common tectosilicate, a mineral of the Zeolite Group, Natrolite Subgroup, which typically occurs as a secondary mineral in vesicles and fractures of basic igneous rocks. It has no economic importance other than for mineral collectors. In the Natrolite Subgroup there are three very common zeolites: scolecite (of Ca), natrolite (of […]