by: Peter Russell
In the last issue of Wat on Earth we covered various aspects of tantalum, an important mineral for electronics and other uses for the 21st century. On a recent visit to the quarries owned by AquaRose, the owners were busy with a variety of projects including accessing the potential for a possible tantalum mine. The Rose Quartz deposit is also starting to yield carving and gem quality material.
Figure 1. Cleaning the quarry wall in the Beryl Pit after the August 25th blast.
The Rose Quartz quarry was mined in the 1920's and 1940's for feldspar, 1930's and 1940's for beryl and 1967-73 for Rose Quartz using industrial mining and blasting techniques which only served to damage the rose quartz. Work recently has involved removing this shattered material to expose undamaged quartz. In the process interesting things have been uncovered. Rose quartz is usually found as tiny crystals, up to a centimetre long. At Quadeville the quartz crystals grew vertically in the core of the pegmatite. The crystals are about 10 to 15 metres across, with sharp crystal faces observed next to kaolin and other minerals in the space between crystals. Mineralogists are studying the reason for the large crystals and the source of the pink colour in the quartz. In some deposits the colouring material is tiny crystals of rutile (titanium dioxide). The Quadeville deposit is thought to be coloured by light interacting with tiny fibrous crystals of dumortierite (aluminum boro-silicate). Dumortierite can be white, pink, and blue. Phosphorous in the quartz may also be a factor in producing the pink colour. The presence of fluorine in the melt may have encouraged the growth of giant quartz crystals.
Pegmatite is a coarse grained igneous rock, similar in composition to granite. Pegmatite is usually found in dikes or lenses and the margins of a batholith. The grain size is one centimetre or more. The composition may be simple or complex and may contain rare elements such as lithium, boron, fluorine, niobium, tantalum, and uranium. Pegmatites represent the last and most water-rich portion of the magma to crystallize and contain high concentrations of elements present only as trace amounts in granitic rocks.
Massive crystals of microcline and albite feldspar surround core of the deposit like a stockade, the quartz crystals grew vertically in the core of the pegmatite. The feldspar is the source of columbite/tantalite crystals. These crystals are of interest due to the tantalum content. A junior mining company has taken options on the quarry to conduct a feasibility study. Funds provided by this mining company have allowed AquaRose to develop the beryl pegmatite north of Quadeville exploring for the extension of the deposit below ground. The first round of blasting was done on August 25th.
Mining activity in these quarries in the 1930's involved extracting beryl crystals which were stock piled. This material was purchased for use in the production of armored steel plating by Germany before the second world war.
Dick and Heather Farmery and David and Renee Paterson are the owners of two pegmatite deposits near Quadeville, Ontario. One is at the Eneas Lake road off highway 515 west of Quadeville and the other is 2 km north of Quadeville. The Beryl Pit is regularly open to visitors. A trespass fee is to be paid at the general store in Quadeville. Visits to the rose quartz mine must be coordinated with the owners of the quarry.