A constituent mineral present in small quantity and not taken into account in identifying a rock.
‘But zircon is rarely present in large quantities in any one rock, making it what geologists call an accessory mineral: a mineral present in such meager quantities that geologists usually pay it little heed.’
‘Titanite is a common accessory mineral in metamorphic rocks, especially those with a high Ca / Al ratio such as limestones and calc-silicate rocks.’
‘Corundum occurs as an accessory mineral in some metamorphic rocks, such as mica schist, gneiss, and crystalline limestone.’
‘It is an uncommon accessory mineral in certain sedimentary carbonate and clay-rich rocks and has been identified as a product of coal-mine fires.’
‘The pegmatites are composed of K-feldspar, quartz, plagioclase and biotite, with titanite, opaque minerals and apatite as accessory minerals.’
‘Sphalerite and lollingite are locally common accessory minerals in this rock.’
‘It is also an important accessory mineral in most mineral deposits formed from high-temperature fluids.’
‘It is an accessory mineral in a variety of igneous and relatively high-rank metamorphic rocks; low-temperature polymorphs are reported from some sedimentary occurrences.’
‘Rutile is widespread in Canada as an accessory mineral in many varieties of crystalline rocks, although good specimens are not commonly encountered.’
‘Asbestos and asbestiform minerals may occur as a natural accessory mineral in other industrial mineral deposits or rocks.’
‘Rutile is a locally important constituent of hydrothermally altered rocks and is often seen as an accessory mineral in a variety of regional and contact-metamorphic settings.’
‘It has been observed as an uncommon accessory mineral in some contact metamorphic deposits and is reported as a rare constituent of some carbonaceous chondrite meteorites.’
‘Subsequent collecting trips to the locality in fall 2000 by Carlson and Ziolkowski resulted in the recovery of many fine specimens of crystallized copper and a suite of accessory minerals.’
‘Garnet of metamorphic origin is a common accessory mineral.’
‘During a multinational mining venture in the summer of 1998, a large miarolitic cavity was excavated that contained abundant red tourmaline and a diverse suite of accessory minerals.’
‘Large tubular gas pockets (often many feet long) lined with amethyst and other accessory minerals, colloquially known as ‘cathedrals,’ are common in the basalts of Rio Grande do Sul, Brazil.’
‘Other associated minerals include olivine (commonly altered to serpentine), phlogopite, enstatite, and many other trace accessory minerals.’
‘The area has been a prolific source of smoky quartz, amazonite, occasional topaz, and other accessory minerals, including albite, fluorite, phenakite, columbite, cassiterite, goethite, and many others.’
‘Garnets are common accessory minerals in granitic pegmatites and are typically members of the spessartine-almandine solid-solution series.’
‘A small amount of gold and the less common accessory minerals were found, including mercury, tennantite, tetradymite; and tetrahedrite.’
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