Lengenbach Quarry, Fäld (Imfeld; Im Feld; Feld), Binn Valley, Wallis (Valais), Switzerland

KAl₂(Si₃Al)O₁₀(OH,F)₂

Crystal System: monoclinic
Colour: white to colorless, silvery-white, and tinged various colors by impurities
Lustre: vitreous, silky, pearly
Habitus: tabular, lamellar, foliaceous, microcrystalline ("sericite")
Hardness: 2½
Fracture: micaceous
Cleavage: perfect on {001}
Density: 2.83 g/cm³ 
Origin and geological occurrence: it is common in several geological enviroments. It occurs in felsic igneous rocks (e.g., granite, granite pegmatites) and metamorphic rocks (e.g., phyllite, schist, gneiss). It is formed in hydrothermal environments and it can be a detrital or authigenic component in sedimentary rocks.

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Samples:

	9E.6 Muscovite Micaceous crystals with white crystals of albite #phyllosilicates
	9E.7 Muscovite Silver-white foliaceous crystals of muscovite with perfect cleavage on {001} and pearly lustre. The size of crystals varies from centimetric to millimetric. Associated with quartz. #phyllosilicates
	9E.13 Muscovite Silver-white foliaceous crystals of muscovite with pearly lustre, deep striation on {001} and perfect basal cleavage on {001} associated with albite #phyllosilicates
	9E.14 Muscovite Micaceous pseudo-hexagonal crystals with minor quartz #phyllosilicates