Quartz monzonite is an intrusive,

felsic In geology, felsic is a modifier describing igneous rocks that are relatively rich in elements that form feldspar and quartz.Marshak, Stephen, 2009, ''Essentials of Geology,'' W. W. Norton & Company, 3rd ed. It is contrasted with mafic rocks, wh ...

igneous rock Igneous rock (derived from the Latin word ''ignis'' meaning fire), or magmatic rock, is one of the three main rock types, the others being sedimentary and metamorphic. Igneous rock is formed through the cooling and solidification of magma or l ...

that has an approximately equal proportion of

orthoclase Orthoclase, or orthoclase feldspar ( endmember formula K Al Si3 O8), is an important tectosilicate mineral which forms igneous rock. The name is from the Ancient Greek for "straight fracture," because its two cleavage planes are at right angl ...

and

plagioclase Plagioclase is a series of tectosilicate (framework silicate) minerals within the feldspar group. Rather than referring to a particular mineral with a specific chemical composition, plagioclase is a continuous solid solution series, more pro ...

feldspar Feldspars are a group of rock-forming aluminium tectosilicate minerals, also containing other cations such as sodium, calcium, potassium, or barium. The most common members of the feldspar group are the ''plagioclase'' (sodium-calcium) feld ...

s. It is typically a light colored phaneritic (coarse-grained) to

porphyritic Porphyritic is an adjective used in geology to describe igneous rocks with a distinct difference in the size of mineral crystals, with the larger crystals known as phenocrysts. Both extrusive and intrusive rocks can be porphyritic, meaning a ...

granitic rock. The plagioclase is typically intermediate to sodic in composition, andesine to oligoclase.

Quartz Quartz is a hard, crystalline mineral composed of silica ( silicon dioxide). The atoms are linked in a continuous framework of SiO4 silicon-oxygen tetrahedra, with each oxygen being shared between two tetrahedra, giving an overall chemical ...

is present in significant amounts.

Biotite Biotite is a common group of phyllosilicate minerals within the mica group, with the approximate chemical formula . It is primarily a solid-solution series between the iron- endmember annite, and the magnesium-endmember phlogopite; more alum ...

and/or

hornblende Hornblende is a complex inosilicate series of minerals. It is not a recognized mineral in its own right, but the name is used as a general or field term, to refer to a dark amphibole. Hornblende minerals are common in igneous and metamorphic ro ...

constitute the dark minerals. Because of its coloring, it is often confused with

granite Granite () is a coarse-grained ( phaneritic) intrusive igneous rock composed mostly of quartz, alkali feldspar, and plagioclase. It forms from magma with a high content of silica and alkali metal oxides that slowly cools and solidifies und ...

, but whereas granite contains more than 20% quartz, quartz monzonite is only 5–20% quartz. Rock with less than five percent quartz is classified as monzonite. A rock with more alkali feldspar is a

syenite Syenite is a coarse-grained intrusive igneous rock with a general composition similar to that of granite, but deficient in quartz, which, if present at all, occurs in relatively small concentrations (< 5%). Some syenites contain larger proport ...

whereas one with more plagioclase is a quartz diorite.Classification of Igneous Rocks
The fine grained

volcanic rock Volcanic rock (often shortened to volcanics in scientific contexts) is a rock formed from lava erupted from a volcano. In other words, it differs from other igneous rock by being of volcanic origin. Like all rock types, the concept of volcan ...

equivalent of quartz monzonite is quartz latite. The term adamellite was originally applied by A. Cathrein in 1890 to

-bearing tonalite (likely a granodiorite) at Monte Adamello, Italy, in 1890, but later came to refer to quartz monzonite. The term is now deprecated. Quartz monzonite porphyry is often associated with

copper Copper is a chemical element with the symbol Cu (from la, cuprum) and atomic number 29. It is a soft, malleable, and ductile metal with very high thermal and electrical conductivity. A freshly exposed surface of pure copper has a pinkish ...

mineralization in the

porphyry copper Porphyry copper deposits are copper ore bodies that are formed from hydrothermal circulation, hydrothermal fluids that originate from a voluminous magma chamber several kilometers below the deposit itself. Predating or associated with those flui ...

ore deposits.

Geographic distribution

United States

In the White Mountains and western highlands of

New Hampshire New Hampshire is a state in the New England region of the northeastern United States. It is bordered by Massachusetts to the south, Vermont to the west, Maine and the Gulf of Maine to the east, and the Canadian province of Quebec to the nor ...

, the Kinsman Quartz Monzonite is an extensive formation that underlies Kinsman Mountain, parts of Franconia Notch, Mount Cardigan, and Mount Sunapee. Stone Mountain in

Georgia Georgia most commonly refers to: * Georgia (country), a country in the Caucasus region of Eurasia * Georgia (U.S. state), a state in the Southeast United States Georgia may also refer to: Places Historical states and entities * Related to t ...

is a large quartz monzonite monadnock. Quartz monzonite extracted from a quarry in Little Cottonwood Canyon was used to build several buildings in

Salt Lake City Salt Lake City (often shortened to Salt Lake and abbreviated as SLC) is the capital and most populous city of Utah, United States. It is the seat of Salt Lake County, the most populous county in Utah. With a population of 200,133 in 2020, th ...

Utah Utah ( , ) is a state in the Mountain West subregion of the Western United States. Utah is a landlocked U.S. state bordered to its east by Colorado, to its northeast by Wyoming, to its north by Idaho, to its south by Arizona, and to its ...

, including

the Church of Jesus Christ of Latter-day Saints The Church of Jesus Christ of Latter-day Saints, informally known as the LDS Church or Mormon Church, is a nontrinitarian Christian church that considers itself to be the restoration of the original church founded by Jesus Christ. The ...

' Salt Lake Temple, Church Administration Building, and

Conference Center A convention center (American English; or conference centre in British English) is a large building that is designed to hold a convention, where individuals and groups gather to promote and share common interests. Convention centers typical ...

, as well as the

Utah State Capitol The Utah State Capitol is the house of government for the U.S. state of Utah. The building houses the chambers and offices of the Utah State Legislature, the offices of the Governor, Lieutenant Governor, Attorney General, the State Auditor and ...

. The large boulders of Joshua Tree National Park in southern California are quartz monzonite. A large pluton in the Atlanta lobe of the Idaho Batholith, near

McCall McCall is a Gaelic surname, of Irish and Scottish origin. Notable people with this surname include: * Andy McCall (footballer, born 1911) (1911–1979), Scottish footballer and manager *Andy McCall (footballer, born 1925) (1925–2014), Scottish f ...

Idaho Idaho ( ) is a state in the Pacific Northwest region of the Western United States. To the north, it shares a small portion of the Canada–United States border with the province of British Columbia. It borders the states of Montana and W ...

, is made of quartz monzonite.Idaho Batholith
/ref> The Guilford Quartz Monzonite and Woodstock Quartz Monzonite, probably comagmatic, are located in central

Maryland Maryland ( ) is a U.S. state, state in the Mid-Atlantic (United States), Mid-Atlantic region of the United States. It shares borders with Virginia, West Virginia, and the District of Columbia to its south and west; Pennsylvania to its north; ...

Australia

Queensland ) , nickname = Sunshine State , image_map = Queensland in Australia.svg , map_caption = Location of Queensland in Australia , subdivision_type = Country , subdivision_name = Australia , established_title = Before federation , established_ ...

, Castle Hill, Mount Stuart and Mount Louisa around

Townsville Townsville is a city on the north-eastern coast of Queensland, Australia. With a population of 180,820 as of June 2018, it is the largest settlement in North Queensland; it is unofficially considered its capital. Estimated resident population, 30 ...

represent a large quartz monzonite province.

References

External links

* {{commonscat-inline Igneous petrology Granitic rocks