Khondalit
Khondalite is the name of a metamorphic rock that emerged from a clayey sedimentary rock at pressures above 5 kilobars and temperatures between 650 ° and 850 ° C. The name was first used in 1902 by geologist TL Walker for rocks from South India ; it is derived from the tribe of the Khond (also Gond ), who were native to Orissa and parts of Andhra Pradesh . Although the rock name is mainly used for metamorphic sedimentary rocks found in India, descriptions of these rocks exist from Antarctica , Burma , Vietnam and North America . As recommended by the IUGS Subcommission on the Systematics of Metamorphic Rocks khondalite are as sillimanite - granulites , or in the presence of a gneiss - texture are called sillimanite paragneiss.
composition
Characteristic of the khondalite is its high content of aluminum-rich minerals. The main components are quartz and feldspar as well as cordierite and sillimanite. Khondalites usually contain 1 to 5% graphite . Depending on the composition of the parent rock prior to metamorphosis, garnet , biotite and orthopyroxes can occur. The texture is usually characterized by a layered alternation of dark and light rock sections, with higher proportions of biotite a gneiss texture can also occur.
Individual evidence
- ↑ Recommendations for the Naming of Metamorphic Rocks , accessed on August 26, 2011
