noun

• 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.’

  More example sentences

  • ‘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.’