The document describes various rock types found in the mountain ranges along India's eastern coast, including the Archean rocks that make up the core of the ranges. It discusses the main rock types of gneisses, charnockites, khondalites, and kodurites. Khondalites are named after the Khond tribe and are often banded rocks containing quartz, feldspar, and graphite. Kodurites are manganese-rich gneisses that can weather to form manganese ore deposits.

1. Godavari river

2.  The mountain ranges extend in the NE-SW direction along the
eastern coast of Orissa to Tamil Nadu.
 The rocks exposure is the Archean rocks that are 50-80 Km in
width.
 The chief rocks are: metamorphosed gneisses, Charnockites,
Khondalites & Kodurites.
 Charnockites shows intrusive relationship with Khondalites.
 In these rocks garnet and sillimanite occur in abundance.

3.  They shows intrusive relation with the country rock, and also shows foliated structure.
 They are acidic in nature and are characterized by the presence of bluish gray of quartz.
 Usually occur in most of mountain ranges of Eastern Ghats like Sheveroy hills, Nilgiri
hills, and palni hills

4.  they are the Garnet-Silimanite-Schist
 They are named after the ‘Khond’ tribe of Andhra
Pradesh.
 They are often banded and contain quartz, feldspar,
and graphite.
 Khondalites are believed to have formed by
plutonic metamorphism of argillaceous sediments.
 The felspathic Khondalites are thought to have
originated by Granitization. On weathering these
rocks give rise to laterite and bauxite
 Khondalites often contain graphite deposits of
commercial importance.
Argillaceous: of rocks or sediment) consisting of or containing clay

5.  They are manganese rich gneisses.
 Composed of potash feldspar, manganese garnet, manganese pyroxene,
quartz and Apatite.
 The Kodurite are the hybrid rocks by the assimilation of metamorphosed
manganiferous sediment and acid igneous rocks.
 On weathering they give rise to Manganese ore diposits.
Apatite:
a widely occurring pale green to purple mineral, consisting
of calcium phosphate with some fluorine, chlorine, and
other elements. It is used in the manufacture of fertilizers.

6.  it is a manganese bearing high grade metamorphic rock.
 It composed of quartz, spessartite, Rhodonite, and small
percentage of Apatite.
 They are formed by the plutonic metamorphism of sediments
rich in Manganese oxide.
 Commonly found in Archean succession of Balaghat-chinwara
area of Madhya Pradesh
Spessartine:
sometimes mistakenly referred to as spessartite,is
a nesosilicate, manganese aluminium garnet species, Mn2+
3Al2(SiO4)3.
The mineral spessartine should not be confused with a type of igneous
rock (a lamprophyre) called spessartite.

7. 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 Greek ῥόδος rhodos, rosy), often
tending to brown because of surface oxidation.