Colin Fergusson and Brian French were killed at the company's Pennyvennie site, in Dalmellington, on 26 February when their vehicle was crushed by a 100 tonne capacity dump truck.
The Ayr Sheriff Court, where the mining firm today pleaded guilty to a breach of the Health and Safety at Work Act, heard the dump truck driver could not see their vehicle because it was in a blind spot.
HSE Inspector Norrie Buchanan described the fatalities as “entirely preventable” but said quarrying remained one of the most dangerous industries to work in.
Mr Buchanan said: “These two deaths were entirely preventable and arose from the clear failure of Scottish Coal to provide suitable means of communication between different vehicles on site in order to reduce the risk of collisions, as well as a failure to manage vehicles on their site.
“It is crucial that additional steps are taken to ensure that the drivers of these dump trucks are aware of other smaller vehicles around them.”
Since 2000 more than 2,700 quarry workers have been injured in the UK, including 21 fatalities.