The district of Visakhapatnam is geologically situated on one of the oldest rocks which has abundant mines of semi-precious stones and is rich in mineral wealth. Illegal mining of semi-precious coloured gems and stones has been in practice for long time in the hilly areas of Eastern Ghats and these stones are then exported to other northern states of the nation. Experts have pointed out that the constant digging for these semi-precious stones and the destruction of medicinal plant bearing rocks is causing a huge loss to the non-renewable wealth of nature. The area of the Eastern Ghats including Visakhapatnam region is made of Pre-Cambrian era rocks [earliest rocks formed in a big basin of geo syncline] which dates back to around 2.9 billion years while the age of the Earth is 4.5 billion years. In the smaller hilly terrains of Vizag like Kailasa, Duvvada and Yarada, Kondalite is the most important rock while in some areas, Leptynites are also found. These ancient rocks are rich in mineral wealth such as bauxite, manganese, limestone and graphite or china clay. Areas including Paderu, Chintapally, Narsipatnam and adjacent village are also storehouse of semi-precious or coloured stones. Within the Kondalite rocks, pegmatite rock bodies lies where these semi-precious stones are found. Many of the colonial era buildings of Vizag are made of these geo-heritage Kondalite rocks.
The main stones found are from the beryl group is the Chrysoberyl (cat’s eye) and alexandrite or Alex as well as moonstone of the feldspar group. Alexandrite is the most valuable of all the mined stones. It’s a bluish green stone that appears like a red flame when torchlight falls on it and which is popularly called, “emerald by day and ruby by night”. Most of these stones are used in making jewellery and have astrological value. According to sources, the famous precious stone – ‘green emerald’ is also found in Borra Caves area near Araku. The market value of these gemstones range from thousands to lakhs depending on their cut and carat. The bigger the carat of the stones, the value will be manifold in multiple proportions.