Diorite


Also found in: Dictionary, Thesaurus, Acronyms, Wikipedia.
Related to Diorite: gabbro, andesite, Quartz diorite

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 ?
The soil layers surrounding the piles were residual soil with thickness of 5 m, weathered diorite with average thickness of 4 m, highly weather diorite with average thickness of 1.7 m, and bearing stratum.
According to drilling logging, both the quartz diorite and carbonate rocks of Lower Permian Maokou Formation are cut by the [F.sub.1] fault below the surface [37].
Zircon from sample DD8-17, a quartz diorite from the northwest Ontario dated at 3002 [+ or -] 2 Ma (Tomlinson et al.
Large zones of auriferous biotite hornfels and silicification within late Paleozoic to Triassic sediments appear to be related to weakly deformed and intensely propylitic altered diorite plugs and stocks in the Copper Mountain area.
The diorite bulky dubbed the Rosetta Stone derives its importance from the fact that it helped Thomas Young and Francois Champollion, pioneers of the modern science of Egyptology, to decipher the ancient Egyptian language by comparing the hieroglyphic text to its counterparts in classical Greek and Demotic, another ancient Egyptian script also inscribed on the stone.
In the depths lies an intrusive diorite stock which is probably genetically related to the mineralization.
It is a tapering block of black diorite, eight feet high and inscribed with forty-four columns of cuneiform.
These gold-rich porphyries are overwhelmingly hosted by composite stocks of diorite to quartz-diorite and, to a much lesser degree, more felsic compositions such as tonalite and monzogranite.
Small and isolated intrusions of diorite, gabbro, gabbronorite, ultramafic rocks, monzonite, syenite and anorthosite constitute about 2% of the area.
Just north of Hooiberg is a weird geological collection of huge diorite boulders, seemingly dumped in a careless manner by some strange force.