THERE’S precious gems in the roads around Mortlake.
Mortlake gem collector Alan Wood said the road-making material dug out of the Mount Shadwell quarry near Mortlake often contained the green-coloured olivine, sometimes with quality high enough to become the peridot gem.
He has made a faceted four-carat peridot gem worth about $450 for a man who found the rock sticking out of the bitumen on a road in Mortlake’s town centre.
Mr Wood, who has been collecting olivine at Mount Shadwell for about 25 years, said the mineral’s value was “way underrated” in the local district.
He said olivine was found in nearly all volcanoes in the south-west but Mount Shadwell was the best site because it had larger grains of the mineral.
Moyne Shire Council’s quarry on the mountain had also made it easier to get access to the olivine “bombs”, lumps of basalt blown out of the volcano that often had olivine in its core.
The “bombs” were often the size of a pigeon’s egg, with a tail, but some could be as large as a car.
The smaller ones could be broken open with a hammer to reveal olivine “but you have to break open quite few bombs” to get deposits of gem quality, he said.
The Mount Shadwell deposits attract collectors from around the world and Mr Wood has supplied specimens to the Melbourne Museum and mineral experts throughout the world.
Mr Wood’s collection of olivine and faceted peridot will be among the many displays at the Warrnambool Gem Club’s biennial show at Warrnambool Primary School this weekend.
The show will also include demonstrations of gem cutting and silver work, sales and trade stalls.