“Kaoleen” is a term used locally in part of south-central Missouri to refer to a chalky, white to tan or buff, porous weathered chert, but the name should be dropped because it is unnecessary (use weathered chert), confusing, and not recognized elsewhere. Most probably the term arose in corruption of the word _kaolin_, which is the name for a true, high-quality clay, to which the leached and weathered chert bears a slight resemblance. Kaolin has the chemical composition of clay (hydrous aluminum silicate), whereas “kaoleen” is impure silica. See the discussion on Weathered Chert. Tripoli Tripoli occurs in the vicinity of Seneca, Newton County, Missouri. It is a light-weight, porous, white to creamy, siliceous rock, which may be scratched because of its softness. Tripoli represents the porous insoluble residue of an earlier rock, which was composed of skeletal insoluble silica and interstitial soluble calcium carbonate (calcite), the latter having been dissolved away by ground water. Tripoli has a chalky appearance but is totally unlike chalk chemically. Tripoli is nearly pure silica, whereas chalk is calcium carbonate. Any tripoli-like rock found in Missouri outside the region of tripoli mines is likely to be a fragment of weathered chert which is described above. Tripoli has been used as an abrasive, a polishing agent, a parting material in molding sand, and a filter rock. Agate Agate is a banded variety of chert. Although the chemical composition of agate is SiO₂, the same as chert, a microscopically fibrous part of it having a waxy luster or varying in color or translucency may give the appearance to the rock that we associate with the name agate. The mineral name chalcedony is given to the fibrous, waxy material. Typical agates are most abundant in Missouri in the glacial and stream gravels in the northern part of the state, although part of the Potosi drusy quartz and chalcedony in the southeast is also prized. The large gravel pit near LaGrange, in the northeast, has furnished many beautiful specimens, not only of agate, but also of petrified wood and fossils. Missouri lapidists and collectors of semi-precious stones find plenty of interesting raw material within their own state. Jasper Jasper is chert which is colored red or yellowish brown by iron oxides. Granite [Illustration: Close view of a granite hand specimen. Feldspar predominates. Quartz appears dark in the photograph, but shows glistening edges and points. From Graniteville.]