Diorite

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diorite

[′dī·ə‚rīt]
(petrology)
A phaneritic plutonic rock with granular texture composed largely of plagioclase feldspar with smaller amounts of dark-colored minerals; used occasionally as ornamental and building stone. Also known as black granite.

Diorite

 

a magmatic rock composed of plagioclase (andesine or oligoclase), hornblende, and more rarely, augite and biotite; sometimes quartz is present. Chemically, diorite is characterized by an average amount of silicic acid (55-65 percent).

Several varieties of diorite may be distinguished: quartz, quartzless, hornblende, augite, and biotite. Its color is gray to greenish-gray, and its structure is characterized by clearly defined idiomorphic plagioclase, which distinguishes it from biotite and amphibole. Diorite is not widespread and as a rule is found with granites and granodiorites, more rarely with other rock; it appears as a local facies.,In addition diorite may form independent stocks, veins, laccoliths, and other intrusive massifs. It is used as a building material and in road building. Some varieties of diorite have many shades of color and lend themselves to polishing; these are used to face buildings and to make such articles as vases, table tops, and pedestals. In ancient Egypt and ancient Mesopotamia diorite was also used for sculpture. Hard, dense, and opaque, diorite is used as a general-purpose sculptural stone to create forms of severe structural design; it also used in fine graphic-linear cutting.


Diorite

 

magmatic rock of paleotype habit, similar to basalt chemically and in its mineral composition. Diorite is characterized by a relatively small silica content (45-52 percent). Its coloring is dark gray or greenish black. The dioritic (ophitic) structure is formed by randomly placed elongated small plagioclase crystals, with augite in the interstices. Diorite is especially distributed in regions with gently sloping stratification of the sedimentary rock that encloses it, as well as among volcanic lava and tufa. Diorites form shallow, congealed bodies (sills and dikes) whose depth varies from a few cm to 200 m or more. Diorite is used for road-building stone and for stone casting.

diorite

Medium- to coarse-grained rock composed essentially of plagioclase feldspar and ferromagnesium minerals.
References in periodicals archive ?
This mineralized structure consisted of a split vein system consisting of white quartz, intervening silicified, pyritic diorite (0.
TSD-10 is inclined at 60 degrees to the west and designed to delineate the eastern contact of the mineralized diorite intersected in TSD-6.
Potassic altered diorite continued to 240 metres downhole and potassic altered pyroclastics were encountered to hole end at 422 metres depth.
Results from the drilling program indicate that gold mineralization is widespread and associated with sulphide mineralization (pyrite) in sheared diorites and altered intermediate metavolcanics.
Geologically, the mine consists mainly of granodiorite interspersed with coarse diorite.
Le pluton du ruisseau Landry se compose de trois unites : du gabbro a de la diorite quartzique, de la monzodiorite quartzique au monzogranite, et du monzogranite.
Other lithotypes include gabbro/quartz diorite and late monzogranite.
Most of the northeastern and southern parts of the Dickie Brook pluton consist of medium-grained gabbro to quartz gabbro and quartz diorite (Fig.
Gabbro is generally medium to dark grey and the grain size varies from fine to medium; quartz diorite is texturally similar to the gabbro but lighter in colour.
Mafic rocks of the Dickie Brook pluton vary in composition, and include gabbro, leucogabbro to quartz gabbro, and diorite to quartz diorite.
In the Landry Brook pluton and Charlo plutonic suite, gabbro/quartz diorite and diabase have Si[O.
Overall, the samples from all units are similar, although diorite/quartz diorite from the Dickie Brook pluton shows the greatest deviation from the norm.