Chert is a sedimentary rock composed of microcrystalline or cryptocrystalline quartz. While usually biological in origin, chert may also occur as a chemical precipitate or a diagenetic replacement--the product of petrified trees. Chert, also known as flint, was a common tool for early peoples during the stone age. It forms in limestone and chalk sediments as silicon dioxide microcrystals which grow into nodules of chert. Chert is found in many mines across the Northern Territory, however this specimen is sourced from the Mount Todd gold mine in Katherine. Its use in weaponry, both during the Stone Age and during the 18th century. Chert produces a spark when struck against steel, meaning t hat it can be used to start fires and fire guns. Chert was thus used in flintlock firearms, in which the gunpowder is ignited by a flint hammer striking a steel plate. Chert was commonly used in the Stone Age as a result of conchoidal fracturing causing very sharp edges, allowing early peoples to fashion weapons and cutting tools. It also rates a 7 on the Mohs Scale, making it a very hard and durable stone that maintains its sharpness. As a result, the significance of chert as a signifier of early indigenous Australian life makes this specimen important. It is also known that chert is a valuable mineral that was used as a trading commodity. Chert has also been valuable during the 1700s, proving itself to a be an important historical specimen in matters of war. A solid silicon dioxide mineral in shades of brown, white, and beigeburke museum, northern territory, chert, flint, minerals, geological specimen, katherine, mount todd gold mine, katherine northern territory