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.
McGraw-Hill Dictionary of Scientific & Technical Terms, 6E, Copyright © 2003 by The McGraw-Hill Companies, Inc.
The following article is from The Great Soviet Encyclopedia (1979). It might be outdated or ideologically biased.

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.

The Great Soviet Encyclopedia, 3rd Edition (1970-1979). © 2010 The Gale Group, Inc. All rights reserved.

diorite

Medium- to coarse-grained rock composed essentially of plagioclase feldspar and ferromagnesium minerals.
McGraw-Hill Dictionary of Architecture and Construction. Copyright © 2003 by McGraw-Hill Companies, Inc.
References in periodicals archive ?
The U-Pb igneous crystallization ages from zircon and monazite in plutonic rocks ranging from dioritic to granitic in the Creignish Hills and North Mountain areas cluster at about 550 Ma (Fig.
Similarly, fresh potassian ferropargasite in the dioritic gneiss contains approximately 0.3 atoms Ti pfu and trace amounts of Ce and Sr, and alters to a mixture of calcite and clinochlore similar in composition to that derived from biotite, but with a lower Mg/Fe ratio.
Igneous bodies in the Wanikande-Wanakom area include dioritic rocks, micrograbbros, nepheline syenites, dolerites, basaltic sills, nephelinites, trachytes, and pyroclastics.
Faulting may also be enhanced given the position of the site along a contact zone adjacent to the eastern edge of the Kathy Road Dioritic Suite.
The landmark development from this project has identified high gold values in veins metres below surface and a comprehensive large scale stockwork vein system that covers the entire underground development and the surfaced exposed dioritic body.
The Van Silver property and surrounding area are characterized by north to northwest-trending roof pendants of volcanic and volcano-sedimentary rocks floating in a sea of dioritic and quartz dioritic rocks of the Coast Plutonic Complex.
Alteration and gold mineralization on the Property are related to subvolcanic andesite-dacite intrusions and the cooling and fluid releases of a dioritic magma.
Plutonic rocks in this area include the Bell Lakes Suite, consisting of three mappable plutons of granodiorite and granite, the Goose Cove Brook Granodiorite, Timber Lake Dioritic Suite, and Indian Brook Granodiorite, all of which are considered as part of the 565-555 Ma calc-alkaline plutonic rocks associated with a continental margin subduction zone (Raeside and Barr 1992).
The two granitoids contain local bodies of the basement consisting of fine-grained doleritic to medium-grained dioritic rocks.
The sequence continues with an Eocene-Oligocene unit composed of conglomerates, sandstones, multicolor tuffs, andesites, breccia and ignimbrite that rests unconformably on the Permo-Lower Triassic volcanic complex and is intruded by Miocene intrusive rocks of varied composition (granodioritic, andesitic, dacitic, dioritic, and granitic).