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Natrolite is a colourless, white, or yellow zeolite mineral consisting of sodium aluminium silicate in the form of needle-like orthorhombic crystals and a relative hardness of 6. Natrolite is most often found in cavities in basalt. It is formed through the alteration of plagioclase feldspar, nepheline or sodalite.
Natrolite was confirmed as a distinct species in 1803.
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Natron is a whitish or yellow mineral that consists of hydrated sodium carbonate and occurs in saline deposits and salt lakes.
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Nepheline is a mineral that has the formulae (Na,K)AlSiO4 and a relative hardness of 6. It is formed mainly in pegmatite associated with nepheline syenite, but may also occur in gneiss and schist. Nepheline is associated with feldspars, calcite, cancrinite, hornblende and sodalite.
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Neptunite is an accessory black-coloured mineral confirmed as a distinct species in 1893 and found in association with aegirine. Neptunite is a silicate of sodium, potassium, lithium, iron, manganese and titanium.
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Niccolite (nickeline) is an arsenide of nickel mineral with the formulae NiAs and a relative hardness of 6. It is a minor ore of nickel and often has a copper-like colour. It was confirmed as a distinct species in 1832, but was mined in the Middle Ages by miners believing it to be a copper ore.
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Nodular refers to appearing as or composed of irregular lumps of rock or a mineral.
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Nosean is a sodium aluminium silicate sulphate mineral with a vitreous lustre discovered by the German mineralogist Karl Nose, after whom it is named, and confirmed as a distinct species in 1815. Nosean is found in extrusive igneous rocks, especially in alkali-rich, silica-poor lavas, and in phonolite. It has a relative hardness of 5 to 5.5.
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Abbreviations
Rocks & Minerals
