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In the Galaxy of stone there is one star that has been shining brightly for over 25 years now. This star is none other than the Indian granite, “Black Galaxy”. This granite from India is also known by various other names including Star Galaxy, Galaxy granite, Ongole Galaxy etc. The allure and endurance of this granite has been tremendous over the years with an estimated sale of almost 3 million cubic meters of this material over the years.
The Black Galaxy granite has a black background with gold colored specks in it. The gold specks are due to the presence of ferrous rich Enstatine (Bronzite). The technical geological name for this granite is Gabbric Anorthosite. The material has a hardness of around 4.5 on the Moh's scale which can be termed as moderately hard. The material takes on a very good polish. The ideal use of this material is in interior applications. Black galaxy can be broadly divided into three types based on the size of the gold colored specks:
1. - large specked Black Galaxy
2. - medium specked Black Galaxy
3. - small specked Black Galaxy
Black Galaxy quarries
Black Galaxy quarries are located in a village by the name of Chimmakurthi in Ongole district in the State of Andhra Pradesh in India. The location is about 350 km north of Chennai. One can reach the quarries by road in around 4 hours or by a convenient train from Chennai (around 6 hours) to Ongole, and then on to the mining areas by road. There are around 44 quarries spread over 400 acres of land. The sizes of the quarries range between 2 and 20 acres each. The quarries are quite mechanized. The equipment in the quarries has been constantly updated and it is common to find the latest mining machinery in operation in the quarries.
The main issue for the quarry owners has been the poor recovery of material from the quarries. In almost every quarry the area that has good deposits is very limited. This has raised significantly the cost of quarrying. However, in spite of these negative factors the output is reasonably high for this colour considering that this is one of the more expensive granites in the world. Most of the deposits are below ground level. There are variations of white lines and black lines in the material in almost all the quarries.
As is the case with most granite and marble quarries all over the world, mining is not done on a scientific basis and the emphasis has been on the extraction of maximum amount of material.
Production of Black Galaxy granite
Around 20000CBM to 25000 cubic meters (CBM) of black galaxy granite is produced every month. Only 30% of this volume is made up of big blocks and which are commonly called gang-saw size blocks. These are blocks of sizes above 2.40m x 1.20m x1.00m. The prices for these gang-saw size blocks range between USD 1600 and USD 2000 per CBM (FOB Chennai port).
A decade ago the European companies would buy the big blocks for processing in their factories but the granite industry in India has developed so much in recent years that European companies now mostly purchase only slabs and tiles. It is the Indian processors who now mostly produce the premium quality slabs and have a ready market for Black Galaxy slabs in the United States, Europe and Australian markets for use as kitchen counter tops, among other applications.
The smaller blocks of Black Galaxy are mainly exported to China. The Chinese market used to have a good demand for the small blocks. 30-40 percent of the small blocks are picked up by them. Rest of small blocks are processed in India.
The main ports for export of black galaxy blocks are those of Chennai and Krishnapatnam. The quarrying area provides employment (direct and indirect) to about 100,000 people in the area.