Blue Spur is a locality in Otago, New Zealand.
Blue Spur is the area of the historic Otago gold rush town and gold mining fields north of the town of Lawrence in the Clutha District.
Alluvial gold may often be found close to a layer of blueish clay.
Miners frequently talk about mining down to the "blue clay", thus a "blue spur" could somehow elucidate the hasty process of digging for the gold pursuing a blueish layer of clay.
Besides these gold rush-related connotations there is a "blue spur flower" (Plectranthus ciliatus), and the "blue spur" in coats of arms.