hornblende


Also found in: Dictionary, Thesaurus, Wikipedia.
Related to hornblende: tremolite, augite, biotite

hornblende:

see amphiboleamphibole
, any of a group of widely distributed rock-forming minerals, magnesium-iron silicates, often with traces of calcium, aluminum, sodium, titanium, and other elements.
..... Click the link for more information. .

Hornblende

 

(1) The most common rock-forming mineral of the group of monoclinic amphiboles (common hornblende). Its approximate chemical composition is Ca2Na[Mg, Fe]4[Al,-Fe][(Si, Al)4O11]2[OH, F]2, with substantial variations in the ratios of basic components and with various element impurities (Na <- K, Ba, Rb; Ca ← TR, Y, Sr, U, W, Mo; Al ← Ga; Mg ← Li; Fe ← Zn, Sc). Hornblende crystallizes in the monoclinic system. It forms long, prismatic needles, irregular grains, and fibrous aggregates of green, black, or brown color. It has a hardness of 5.5–6 on Mohs’ scale and a density of 3,100–3,300 kg/m3. Hornblende is characterized by two directions of well-developed cleavages intersecting at an angle of 124°.

Common hornblende is characteristic of intrusive rocks (granodiorites, syenites, diorites, hornblende gabbros), effusive rocks (andesites, basalts, porphyrites), and metamorphic (am-phibolites, hornblende gneisses) rocks. Common hornblende is a relatively stable mineral, but when acted upon by hydrothermal solutions it alters to chlorite, epidote, calcite, and quartz. In the process of weathering, it decomposes to form opal, carbonates, and various other minerals.

(2) The subgroup of calcium aluminiferous amphiboles that includes common hornblende, edenite, oligoclase, pargasite, and hastingsite.

REFERENCES

Deer, W. A., R. A. Howie, and J. Zussmann. Porodoobrazuiushchie mineraly, vol 2. Moscow, 1965. (Translated from English.)
Lodochnikov, V. N. Glavneishie porodoobrazuiushchie mineraly, 5th ed. Moscow, 1974.

A. S. MARFUNIN

hornblende

[′hȯrn‚blend]
(mineralogy)
A general name given to the monoclinic calcium amphiboles that form an extensive solid-solution series between the various metals in the generalized formula (Ca,Na)2(Mg,Fe,Al)5(Al,Si)8O22(OH,F)2.

hornblende

a black or greenish-black mineral of the amphibole group, found in igneous and metamorphic rocks. Composition: calcium magnesium iron sodium aluminium aluminosilicate. General formula: (Ca,Na)2.3(Mg,Fe,Al)5Si6(Si,Al)2O22(OH)2
Mentioned in ?
References in periodicals archive ?
Garnet-bearing amphibole schists exhibit schistose structure defined by the alignment of actinolite, hornblende and chlorite and granonematoblastic and locally porphyroblastic and poiquiloblastic textures.
Petrology, geochemistry and geochronology of the Arquia Complex's metabasites at the Pijao-Genova sector, Central Cordillera, Colombian Andes
2], suggesting crystal fractionation of hornblende ([+ or -]pyroxene) and Fe-Ti oxide (Fig.
Interaction of the lithospheric mantle and crustal melts for the generation of the Horoz Pluton (Nigde, Turkey): whole-rock geochemical and Sr-Nd-Pb isotopic evidence/Litosfaarilise vahevoo ja maakooretekkega magmade suhted Horozi intrusiooni (Turgi) tekkes kivimi geokeemiliste ning Sr-Nd-Pb isotoopgeoloogiliste andmete alusel
39]Ar hornblende cooling ages of 555 [+ or -] 5 Ma apparently from the Marble Mountain biotite granodiorite unit (based on approximate location shown by Keppie et al.
Field relations, age, and tectonic setting of metamorphic and plutonic rocks in the Creignish Hills--North Mountain area, southwestern Cape Breton Island, Nova Scotia, Canada
The presence of euhedral zircon and hornblende (Plates 2 to 6) indicate that ash falls have contributed to this sandstone.
MODAL ANALYSIS OF SANDSTONE AND SILTSTONE LITHOFACIES FROM NORTHLAND ALLOCHTHON ROCKS, NEW ZEALAND
Ectomycorrhizal weathering of the soil minerals muscovite and hornblende.
The multifunctional role of ectomycorrhizal associations in forest ecosystem processes
5d), indicative of pyroxene or hornblende fractionation.
Igneous Rock Associations 11. The geology and petrology of seafloor volcanic rocks of the northeastern Pacific Ocean, Offshore Canada
M]) of the rocks, and single crystal magnetic properties, we have made the following assumptions: 1) magnetic susceptibility of LF2 metabasite is dominated by a paramagnetic contribution which may be dominated by hornblende AMS ([k.
Fabricas magneticas y analisis cuantitativo de texturas mediante difraccion neutronica de tiempo de vuelo: ejemplos en tectonitas (NO del Macizo Iberico, Espana)
Gravel did show the lowest phosphorus removal efficiency (21%) followed by ironstone and hornblende both with a 33% efficiency.
Recirculating vertical flow constructed wetland: green alternative to treating both human and animal sewage
An inclusion made of hornblende, a group of silicate minerals, yielded similar results.
Plate tectonics may have had an early start: ancient zircon crystals imply activity during Hadean eon
Back then, "with no headlands to bump into, the beach sand was free to move, allowing the zircon, pink garnet, green hornblende and other minerals eroding off of southern Oregon's Klamath Mountains to move north and mingle with flecks of dark green augite and brown hornblende sifting down the rivers draining the central Coast Range," she writes.
Beach trash tales
The K-Ar cooling age for hornblende will normally be older than the cooling age for biotite from the same rock, and from those ages one can calculate the approximate rate of uplift from 16 to 11 kilometers for the rock body in question.
How old is it? How do we know? A review of dating methods--Part Three: thermochronometry, cosmogenic isotopes, and theological implications
Hornblende alternation and fluid inclusions in the Kardla impact crater, Estonia: evidence for impact-induced hydrothermal activity.
Impact-induced and diagenetic changes in minerals in the sandy ejecta of the Kardla crater, NW Estonia/Meteoriidiplahvatuse mojul ja diageneesi valtel tekkinud mineraalterade muutused Kardla kraatrit umbritsevas liivakas valjapaiskelasundis

Encyclopedia browser ?
Full browser ?