Definition of acicular in US English:



  • (chiefly of crystals) needle-shaped.

    • ‘In the Monte Calvario area, the fluoro-edenite mineralization process yielded mainly prismatic, evenly sized acicular crystals.’
    • ‘Further collecting on the mine dump during fall 2002 produced additional cubic and octahedral cuprite microcrystals, along with beautiful sprays of tiny acicular malachite crystals.’
    • ‘All of the acicular crystals are late Neoproterozoic’
    • ‘It occurs as sky-blue acicular crystals associated with hydrozincite and hemimorphite at the Billy Springs mine near Mount Fitton, and at the Mount Malvern mine, Clarendon, South Australia.’
    • ‘The acicular crystals are sometimes intergrown or twinned, causing a distortion that results in seemingly single crystals with relatively fat bases tapering to pointed terminations.’
    • ‘It occurs as smooth compact clusters of dark blue-green acicular crystals, typically in association with hemimorphite and occasionally with conichalcite and agardite in all the mines.’
    • ‘Small acicular rutile crystals are found in cavities in various quarries in the Carrara, Tuscany district, Italy.’
    • ‘They often have grown around pre-existing acicular goethite crystals in random orientation, clearly demonstrating the quartz to be of a later growth.’
    • ‘Groutite is observed as small, lustrous black, acicular crystals to 1/8 inch long that occur directly on the quartz or chalcedony.’
    • ‘Eckel reported the presence of acicular pyrite crystals.’
    • ‘As the temperature of its formation becomes higher the acicular nature becomes less accentuated, the needles increasing in size’
    • ‘Wollastonite or calcium metasilicate is a naturally occurring industrial mineral that has an acicular structure.’
    • ‘The largest amphibole crystals are embedded in the rock matrix, whereas the smaller acicular crystals line the hollows.’
    • ‘Epididymite was known several years ago from a few small (millimeter-sized) crystals that occurred on some specimens and also as inclusions of white acicular crystals in smoky quartz.’
    • ‘Sukow suggested that the coloration may be due to aggregates of acicular crystals of copper minerals scattered or concentrated throughout the datolite nodule.’
    • ‘It occurs as bright blue, radiating sprays or spheres of acicular crystals.’
    • ‘A few quartz specimens have included yellow to dull orange acicular crystals, identified by quantitative analysis as aegirine.’
    • ‘The majority of the zircon crystals from the three samples are light yellow, well-faceted, acicular crystals with few to no signs of mechanical abrasion.’
    • ‘Some wire silver from the White Raven and Black Jack mines of the Ward district, Boulder County, were coated with acicular crystals of primary acanthite.’
    • ‘Dark green, acicular crystals of actinolite can be collected from this quarry, which is smaller and older than the Metronite quarry.’
    sharp, spear-like, needle-like, spear-shaped, v-shaped, tapering, tapered, cone-shaped, conic, conical, acute, sharp-cornered, wedge-shaped, sharp-edged, edged, jagged, spiky, spiked, barbed
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Early 18th century: from late Latin acicula ‘small needle’ (diminutive of acus) + -ar.