Despite decline in the production of coal, crude oil and natural gas, the index of eight core industries rose to 6.6 per cent during last month. It was 3.8 per cent in October last year.According to data released by Commerce Ministry, the cumulative growth of coal, crude oil, natural gas, refinery products, fertilizers, steel, cement and electricity industries was 4.9 per cent during first seven months of the current fiscal compared to 2.8 per cent of corresponding period of previous year. The production of coal declined by 1.6 per cent in October this year while the production of steel rose by 3.2 per cent during this period.