of the centers which made use of agate on an industrial scale. Where in the beginning locally found agates were used to make all types of objects for the European market, this became a globalized business around the turn of the 20th century: Idar-Oberstein imported large quantities of agate from Brazil, as ship's ballast. Making use of a variety of proprietary chemical processes, they produced colored beads that were sold around the globe. Agates have long been used in arts and crafts. The sanctuary of a Presbyterian church in Yachats, Oregon, has six windows with panes made of agates collected from the local beaches. Industrial uses of agate exploit its hardness, ability to retain a highly polished surface finish and resistance to chemical attack. It has traditionally been used to make knife-edge bearings for laboratory balances and precision pendulums, and sometimes to make mortars and pestles to crush and mix chemicals. Health impact Respiratory diseases such as silicosis, and a higher incidence of tuberculosis among workers involved in the agate industry, have been studied in India and China. See also Amber Amethyst Aqeeq Aquamarine Citrine Diamond Emerald Garnet Geode Kyanite Labradorite Lithophysa Moonstone Opal Peridot Rose Quartz Swiss Blue Topaz Thunderegg Tiger's Eye Topaz Tourmaline Citations General and cited references Cross, Brad L. and Zeitner, June Culp. Geodes: Nature's Treasures. Bardwin Park, Calif.: Gem Guides Book Co. 2005. Hart, Gilbert "The Nomenclature of Silica", American Mineralogist, Volume 12, pages 383–395, 1927 International Colored Gemstone Association, "Agate: banded beauty" "Agate", Mindat.org, Hudson Institute of Mineralogy Moxon, Terry. Agate: Microstructure and Possible Origin. Doncaster, S. Yorks, UK: Terra Publications, 1996. Pabian, Roger, et al. Agates: Treasures of the Earth. Buffalo, New York: Firefly Books, 2006. Schumann, Walter. Gemstones of the World. 3rd edition. New York: Sterling, 2006. External links "Agates", School of Natural Resources, University of Nebraska-Lincoln (retrieved 27 December 2014). Hardstone carving Silicate minerals Symbols of South Dakota