PHOSPHATE MINERALS, VICTORIA

© Copyright, 2000 by R.A.Kanen, All Rights Reserved

Victoria has a diverse variety of mineral occurrences. One of the best known and most widespread is the phosphate minerals. Victoria only ever had a single phosphate mine, at Phosphate Hill, Mansfield, where a number of trenches were cut to extract the shallow phosphate deposits. The phosphate deposit at Mansfield is of low grade and was difficult to concentrate, resulting in closure of the State Run Mine some 40-50 years ago. The trenches and phosphate deposits are still exposed at Phosphate Hill. The phosphate deposit itself primarily consists of phosphate enriched green shales and fossiliferous siltstones/sandstones. Much of the calcareous material has been altered to phosphate rock and a variety of phosphate minerals also occur. Most of the minerals and crystals are very small, but occasional larger specimens can be found. The phosphate minerals include wavellite, variscite and turquoise. Turquoise occurs as small, blue transparent crystals and as thin opaque turquoise veins. There are also green and bluish variscite coatings and veins and greenish wavellite radiating and globular clusters.

Most of the specimens at Mansfield are very small. A number of other localities around Victoria are also rich in phosphate minerals. Not all of them occur in phosphate enriched shales, although this is the most widespread type of occurrence. Lake Boga Granite Quarry is notable for its beautiful apatite crystals and Wannon Falls, near Apollo Bay has beautiful vivianite crystals. The Edi-Cheshunt slate belt adjascent to the King River Valley contains widespread turquoise along most of its strike length. The veins of turquoise are a few millimeters to one centimetre wide and contain mostly soft, friable turquoise, although occasional hard patches do occur.

The Museum of Victoria has published a book on the Phosphate Minerals of Victoria

Thin Turquoise Vein from the Edi-Cheshunt Slate Belt

Radiating Wavellite Crystals from Mansfield