Khondalite Rock formations at Rushikonda

Khondalite is a foliated

metamorphic rock Metamorphic rocks arise from the transformation of existing rock to new types of rock in a process called metamorphism. The original rock ( protolith) is subjected to temperatures greater than and, often, elevated pressure of or more, caus ...

. In India, it is also called ''Bezwada Gneiss'' and ''Kailasa Gneiss''. It was named after the Khond tribe of

Odisha Odisha (English: , ), formerly Orissa ( the official name until 2011), is an Indian state located in Eastern India. It is the 8th largest state by area, and the 11th largest by population. The state has the third largest population of ...

and

Andhra Pradesh Andhra Pradesh (, abbr. AP) is a state in the south-eastern coastal region of India. It is the seventh-largest state by area covering an area of and tenth-most populous state with 49,386,799 inhabitants. It is bordered by Telangana to the ...

because well-formed examples of the rock were found in the inhabited hills of these regions of eastern

India India, officially the Republic of India (Hindi: ), is a country in South Asia. It is the seventh-largest country by area, the second-most populous country, and the most populous democracy in the world. Bounded by the Indian Ocean on the so ...

Distribution

Khondalite rocks at a hillock near Anandapuram

Khondalite is found in the

Eastern Ghats The Eastern Ghats are a discontinuous range of mountains along India's eastern coast. The Eastern Ghats pass through Odisha, Andhra Pradesh to Tamil Nadu in the south passing some parts of Karnataka as well as Telangana. They are eroded and cut ...

between

Vijayawada Vijayawada, formerly known as Bezawada, is the second largest city in the Indian state of Andhra Pradesh and is a part of the state's Capital Region. It is the administrative headquarters of the NTR district. Its metropolitan region comprises NT ...

and

Cuttack Cuttack (, or officially Kataka ) in Odia is the former capital and the second largest city in the Indian state of Odisha. It is the headquarters of the Cuttack district. The name of the city is an anglicised form of ''Kataka'' which literall ...

in India. but the term khondalite is also used to describe other rocks of similar composition found elsewhere in India as well as in

Burma Myanmar, ; UK pronunciations: US pronunciations incl. . Note: Wikipedia's IPA conventions require indicating /r/ even in British English although only some British English speakers pronounce r at the end of syllables. As John Wells explai ...

Sri Lanka Sri Lanka (, ; si, ශ්‍රී ලංකා, Śrī Laṅkā, translit-std=ISO (); ta, இலங்கை, Ilaṅkai, translit-std=ISO ()), formerly known as Ceylon and officially the Democratic Socialist Republic of Sri Lanka, is an ...

, the northeastern Helanshan region and the

Inner Mongolia Inner Mongolia, officially the Inner Mongolia Autonomous Region, is an autonomous region of the People's Republic of China. Its border includes most of the length of China's border with the country of Mongolia. Inner Mongolia also accounts for a ...

region of China.

Composition

Khondalite is

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 form ...

–

manganese Manganese is a chemical element with the symbol Mn and atomic number 25. It is a hard, brittle, silvery metal, often found in minerals in combination with iron. Manganese is a transition metal with a multifaceted array of industrial alloy use ...

-rich

garnet Garnets () are a group of silicate minerals that have been used since the Bronze Age as gemstones and abrasives. All species of garnets possess similar physical properties and crystal forms, but differ in chemical composition. The different s ...

–

rhodonite Rhodonite is a manganese inosilicate, (Mn, Fe, Mg, Ca)SiO3 and member of the pyroxenoid group of minerals, crystallizing in the triclinic system. It commonly occurs as cleavable to compact masses with a rose-red color (the name comes from the G ...

schist Schist ( ) is a medium-grained metamorphic rock showing pronounced schistosity. This means that the rock is composed of mineral grains easily seen with a low-power hand lens, oriented in such a way that the rock is easily split into thin flakes o ...

. It may also contain

sillimanite Sillimanite is an aluminosilicate mineral with the chemical formula Al2SiO5. Sillimanite is named after the American chemist Benjamin Silliman (1779–1864). It was first described in 1824 for an occurrence in Chester, Connecticut. Occurrence ...

and

graphite Graphite () is a crystalline form of the element carbon. It consists of stacked layers of graphene. Graphite occurs naturally and is the most stable form of carbon under standard conditions. Synthetic and natural graphite are consumed on large ...

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) feldsp ...

may occur in some cases.

Formation

Khondalites are considered to be

metasedimentary In geology, metasedimentary rock is a type of metamorphic rock. Such a rock was first formed through the deposition and solidification of sediment Sediment is a naturally occurring material that is broken down by processes of weathering and er ...

rocks formed during Archaean era. According to

Lewis Leigh Fermor Sir Lewis Leigh Fermor, OBE, FRS (18 September 1880 – 24 May 1954), was a British chemist and geologist and the first president of the Indian National Science Academy and a director of the Geological Survey of India (1930-1935). His son was ...

, the khondalite and the related

charnockite Charnockite () is any orthopyroxene-bearing quartz-feldspar rock formed at high temperature and pressure, commonly found in granulite facies metamorphic regions, ''sensu stricto'' as an endmember of the charnockite series. Charnockite series Th ...

of the Eastern Ghat region were formed when the Eastern Ghat belt was faulted and buried. It was uplifted later, bringing these metamorphic rocks to the surface.

Use

Khondalites weather easily but still have been used in buildings and temples, for example, the

Konark Sun Temple Konark Sun Temple is a (year 1250) Sun temple at Konark about northeast from Puri city on the coastline in Puri district, Odisha, India.Jagannath Temple The Jagannath Temple is an important Hindu temple dedicated to Jagannath, a form of Vishnu - one of the trinity of supreme divinity in Hinduism. Puri is in the state of Odisha, on the eastern coast of India. The present temple was rebuilt f ...

References

Gneiss Metamorphic rocks Geology of India Geology of Andhra Pradesh {{Petrology-stub

Distribution

Composition

Formation

Use

See also

References