Bundaberg Gem and Mineral Soc. Inc.
Kendalls Rd, Bundaberg, QLD 4670 - PO Box 386, Bundaberg, QLD 4670
ph: 07 4155 1500 (club hours)
email : email@example.com
WHAT IS LAPIDARY?
The word Lapidary comes from the Lapis or Stone and means "of pertaining to stones". Not all stones are worth cutting and polishing. The Lapidary is the artist who forms the stone into decorative pieces.
The most common stone is Quartz, which has many other names - Agate, Amethyst, Citrine, even Petrified Wood is a form of Quartz.
The Diamond is the only stone that cannot be cut and polished with general Lapidary equipment. Diamond cutters are not generally referred to as Lapidaries.
Lapidary is the process of shaping the stone with course grinding wheels, then working your way through different "grades" of course wheels or sandpapers to obtain a smooth finish, with the final process being the polish. The polishing is usually done on a soft material pad, this may be carpet or leather, which is placed on a wheel with a motor attached or you can just cover a wooden block with the material of choice.
Usually the first item that a beginner learns is how to "cut a cabachon (cab)" which is generally a gem stone that will finish with a flat back and domed or rounded top. This final shape can be round, oval, square or rectangular.
Colored or patterned stones are usually cut as cabs, agate and petrified wood being the most popular.
Transparent or colorless stones are usually faceted which entails a series of flat polished surfaces known as facets that reflect light through the stone.
Most lapidary work is done using motorised equipment starting with grinding wheels to form the shape using silicone carbide wheels, then several grades (roughness) of sandpaper, until ready for the final polish which is usually done with cerium or tin oxide.
Large rocks are usually cut with a diamond coated or edged saw blade, this can be done on a small bench top machine similar to a tile cutter or a large enclosed saw which uses oil as the lubricant, this is more for larger stones.
When working with stones, be it cutting, sawing or polishing, water is used, as this helps keep the stone cool and assists with lubrication. It is very important that the stone be kept cool when being worked on, if the stone gets too hot, it can cause cracks or even break, this is especially important when working with soft stone like Opal.