The second day of our visit to Birdlings Flat, Petra and I visited Vince and Colleen Burke’s Gemstone and Fossil Museum on Hillview Road. This time, Colleen opened up the Museum for us and we got to talk with her about Birdlings Flat and the stones in the collection. Vince then took over from her after about 15-20 minutes. Petra bought a good-sized batch of agatised wood which we will have a go at polishing sometime. Vince generously gave her three pieces of polished agatised wood, to give her an idea of the end product of polishing. Agatised wood is a form of petrified wood and is in effect a fossil. It forms when plant material is buried by sediment and thus protected from the decaying action of oxygen and organisms. Groundwater rich in dissolved solids flows through the sediment replacing the original plant material with minerals such as silica, calcite and pyrite or another inorganic material such as opal. The result is a fossil of the original woody material that often shows preserved details of the bark, wood and cellular structures. “Agatised” wood is wood that has been replaced by agate, a form of chalcedony or microcrystalline quartz.
After about 30 to 40 minutes at the Museum, we moved onto the beach and spent nearly three hours fossicking for stones, walking eastwards right up to the end of the beach where it butts up against Banks Peninsula. We collected a few kilograms of stones, and returned the next day to collect even more. The next post will look in more detail at the variety of these stones.
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