The district of Vizag is located geologically on some of the oldest rocks that are rich in mineral wealth. These rocks also happen to constitute some of the best semi-precious stones also. While mining for these semi-precious stones is illegal, mining for them is still prevalent in the hilly areas of Eastern Ghats. These stones are then later exported to other states in the North.
Apart from the illegality of it all, the constant digging for these stones is causing great damage to non-renewable wealth of nature by destructing the rocks that bear medicinal plants. This particular area of the Eastern Ghats, including Visakhapatnam, is made of Pre-Cambrian era rocks that date back to 2.9 billion years – almost half the age of Earth, 4.5 billion years. These rocks are some of the earliest rocks formed in a huge basin of geo syncline.
In the terrains of Vizag – in Kailasa, Duvvada and Yarada – kondalite is the rock that is prevalent. In some areas, leptynites are also found. In fact, most of the colonial buildings in Vizag are made of these geo-heritage kondalite rocks. These ancient rocks are rich in mineral wealth such as bauxite, manganese, limestone and graphite or china clay. These hilly terrains also happen to be laden with semi-precious stones, especially in Paderu, Chintapally, Narsipatnam and adjacent villages. Hidden in the kondalite rocks are pegmatite rock bodies housing these semi-precious stones.
Most of the semi-precious stones found are chrysoberyl (cat’s eye), alexandrite or alex and moonstone of the feldspar group. Alexandrite is the one that’s the most valuable of the lot – a bluish green stone that glows red when light of a torch falls on it. It is popularly referred to as emerald by day and ruby by night. Most of these semi-precious stones have astrological value and are used in making jewellery.
Reportedly, stone green emerald can be found at Borra Caves, and based on the cut and carat, the value of these stones range between thousands to lakhs each.