The Castle-an-Dinas quarry, at Ludgvan, near Penzance, was formerly owned by Castle Granite Ltd, which went into administration in April.



The council said the move secured 12 jobs and guaranteed supplies of granite for building and road works aggregates.



It added that the move made financial sense, as its highways service alone bought about 100,000 tonnes of bitumin every year, costing about £4.5m.



'Remain competitive'



The council said that the quarry would be wholly owned and incorporated within the council and it also planned to sell stone products and aggregates from the quarry, for which there was a strong local market.



It is also considering a ready-mixed concrete production facility.



But Arthur Hooper, head of highways at Cornwall Council, said it was not the council's intention to impact on other similar suppliers in Cornwall.



He said: "Providing other suppliers remain competitive, they shouldn't be affected.



"We will also be seeking other external suppliers because, geographically, we don't anticipate taking material from west Cornwall into mid or north Cornwall."