miarolitic


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miarolitic

[¦mē·ə·rō¦lid·ik]
(petrology)
Of igneous rock, characterized by small irregular cavities into which well-formed crystals of the rock-forming mineral protrude.
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References in periodicals archive ?
Unidirectional Solidification Textures, Miarolitic Cavities and Orbicles: Field Evidence for the Magmatic To Hydrothermal Transition in Intrusion-Related Mineral Deposits.
Foster occurs in miarolitic cavities containing gem-quality fluorite, microcline, phenacite ([Be.sub.2]Si[O.sub.4]), smoky quartz, and topaz.
(3) The altered dolomites and bioclastic limestones of Kuangshanchang, carbonates from strata in the periphery of the mining area, and miarolitic calcites have similar C-O isotopic compositions, with most of these compositions projecting within the region of marine carbonates.
Some would say that the world's most attractive specimens of goethite are the fan-sprays of lustrous, brownish red bladed crystals from miarolitic cavities in the granite of the Pikes Peak batholith, Colorado.
Miarolitic cavities are present locally but are generally uncommon (Wolfson 1983).
During this time smoky quartz was being mined from other miarolitic pegmatites some kilometers to the east of the Volynsk piezoelectric quartz deposit.
The upper margin of the granite consists of an almost continuous layer of fine-grained, pink, felsic rock varying from featureless felsite to microgranite with abundant granophyric intergrowth and drusy miarolitic cavities, to rhyolite porphyry that is commonly spherulitic.
At intervals over the past four years, John and Dean have been opening isolated miarolitic cavities in exposures of granite in the Santa Teresa Mountains, north of the town of Klondyke in Graham County.
Parts of the aplitic to porphyritic phase of the GRII contain miarolitic cavities, comb quartz layers, and unidirectional solidification textures (UST), suggesting fluid saturation and/ or undercooling of the parental magma (Kirkham and Sinclair 1988).
These miarolitic cavities in the Pikes Peak granite get up to 4.5 meters deep, and one great microcline/quartz crystal plate in Adam's room measures about 20 X 60 cm; however, the prettiest pieces are miniature-size single crystals and tightly intergrown crystal clusters of fluorite, a few with shining, golden brown sprays and fans of acicular goethite crystals to 5 cm clinging onto their sides.