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 ?
An intrusive dioritic unit has been intersected at all 3 drill target areas and may represent a long but narrow intrusion of regional significance that has been injected into a zone of structural weakness.
North of the area of Figure 2, zones with strongly sheared lithologies continue northward for at least 5 km, into the Timber Brook Dioritic Suite, and may represent an extension of this zone of movement.
All of these blocks are dominated by metasedimentary, in some areas gneissic, rocks, intruded by varied granitic and dioritic rocks with ages of ca.
Drill holes 10WR07 through 11WR10, have intersected a consistent upper stratigraphic package with quartz veined, brecciated and hornfelsed sediments and volcanic rocks with minor dioritic intrusive units overlying a lower package of thinly bedded siltstones, sandstones and minor conglomerates.
Gold mineralization at Santoy Gap is hosted within a system of sheeted, shear-hosted quartz veins, silicified biotite-diopside schist and silicified granitic to dioritic dykes.
2003) concluded that the Baring Granite is approximately contemporaneous with gabbroic and dioritic components of the suite.
They intrude older limestones and sandstones, as well as older dioritic intrusive rocks.
Gold mineralization at Lindero is intrusive-hosted within a dioritic porphyry.
They are intruded by comagmatic dioritic to granitic plutons which have also yielded ages of ca.
Drill Holes R05-03 (230az/-55dip) and R05-04 (042az/-45dip) were collared to test the southwest trending contact zone between ultramafic intrusive unit to the southwest and dioritic intrusive and Takla volcanic rocks to the northeast.
Hole CP024 intersected a dioritic intrusive carrying porphyry gold-copper mineralization, returning 59.
The rocks are grey to locally pink, fine- to medium-grained, weakly foliated quartz monzodiorite with abundant dioritic enclaves, generally less than 20 cm in diameter.