Olivine is an olive-green, grey-green, or brown mineral occurring widely in basalt, peridotite, and other basic igneous rocks.
It is a silicate containing varying proportions of magnesium, iron, and other elements.
Mortlake is situated at the foot of Mount Shadwell, formed 25,000 years ago. It is believed that it last erupted about 5,000 years ago. The large ejected rocks are called volcanic bombs. They are often egg shaped because they cooled as they were being thrown through the air. These bombs can contain olivine, a green crystal also known as peridot, the birthstone for August.
Mount Shadwell Quarry is fully owned and operated by Moyne Shire Council and provides scoria products to the construction and roadwork industries, as well as farmers, trades and the home handy person. The quarry is located 3km north of Mortlake on the Ararat-Mortlake Road, and provides products including crushed rock for roadworks, fine aggregate, dust for pipe bedding and course aggregate for filters and landscaping.
The quarry was established in the 1920s to provide railway ballast and as a source of material for road construction. It has operated for many years under the control of the previous Shire of Mortlake, and now Moyne Shire Council.
Fossicking is available on Friday, Saturday and Sunday. Bookings are essential. To book please contact the Information Centre.