Barras Quarry is located on the southern flank of Bruxie Hill inland and to the south of Stonehaven, it is also known as Cotbank Quarry. Agate material was being removed from this locality as early as the 1960’s. It was opened by the local farmer for the supply of hardcore material. 

The best and most productive area was on the eastern side of the quarry where occasionally, as well as agates, amethyst and smoky geodes have been removed.

The best agates from here are blue-grey in colour but occasionally ones are found with subtle pastel shades of pink or purple. They also display flow bands associated with white segregation spots that give the best agates from here their distinctive appearance.

This quarry lies in the lavas of Old Red Sandstone age.