|See also mica a brownish mica consisting of a hydrous silicate of potassium, magnesium, and aluminium, occurring principally in metamorphic limestones and ultrabasic rocks. Formula: KMg3AlSi3O10(OH)2|
|[C19: from Greek phlogōpos of fiery appearance, from phlox flame +ōps eye]|
|phlogopite (flŏg'ə-pīt') Pronunciation Key
A yellow to dark-brown mica. Phlogopite is monoclinic and is usually found in limestone. It is used in insulation. Chemical formula: K(Mg,Fe)3AlSi3O10(OH)2.
basic aluminosilicate of potassium, magnesium, and iron that is a member of the common mica group. Varieties that contain only small amounts of iron are economically important as electrical insulators. Phlogopite occurs typically as a metamorphic product (e.g., in crystalline metamorphosed limestones) and also in ultramafic igneous rocks. Phlogopite forms a chemical substitution series with biotite, from which it is arbitrarily distinguished by a magnesium-to-iron ratio greater than 2:1. For detailed physical properties, see mica (table)
Learn more about phlogopite with a free trial on Britannica.com.