After oil and natural gas, the Krishna River basin seems to be ideal for diamond mining.
The search for gemstones in the state has been extended to areas beyond Vijayawada and up to the estuary of Krishna with the Geological Survey of India finding evidence of precious stones in this hitherto unexploited region.
Till date the area between Sangam (confluence of Tungabhadra and Krishna in Mahbubnagar district) and Prakasam Barrage in Vijayawada was recognised as the diamond zone. However, studies by the GIS have now revealed that the diamond zone extends well beyond Vijayawada and up to the shores of Avanigadda and Nagayalanka in Krishna district and Repalle in Guntur district.
Penna River, downstream of Somasila, is another new area with prospects of diamond reserves. The reserves may continue well into the sea, offshore of Krishna and Penna, say experts.
The mapping of the geological terrain of coastal areas dating back to the last glacial maximum (18,000 years ago) and beyond shows that the palaeo-channels and channel bars comprising diamond-bearing gravels extend into the lower part of the Krishna delta and even into the near shore area.
According to GSI, about 18,000 years ago Krishna as well as the Penna rivers had extended courses joining the sea at lower levels. “The palaeo-channels of Krishna and Penna in their delta and offshore areas may also form important diamond prospects in select zones,” GSI’s new “Quaternary Maps” point out. Quaternary is the current period in the Cenozoic era on the geological timescale. The diamonds were formed during this period.
Diamond-bearing gravels have also been found in Chennuru and Kanu-parthy, along the upper reaches of the Penna.