Laserfiche WebLink
ROCK CLASSIFICATION <br />(Based on ASTM C-294) <br />Sedimentary Rocks <br />Sedimentary rocks are stratified materials laid down by water or wind. The sediments may be <br />composed of particles or pie-existing rocks derived by mechanical weathering, evaporation or by <br />chemical or organic origin. The sediments are usually indurated by cementation or compaction. <br />Chert Very fine-grained siliceous rock composed of micro-crystalline or cyrptocrystalline <br />quartz, chalcedony or opal. Chert is various colored, porous to dense, hard and <br />has a conchoidal to splintery fracture. <br />Claystone Fine-grained rock composed of or derived by erosion of silts and clays or any <br />rock containing clay. Soft massive and may contain carbonate minerals. <br />Conglomerate Rock consisting of a considerable amount of rounded gravel, sand and cobbles <br />with or without interstitial or cementing material. The cementing or interstitial <br />material may be quartz, opal, calcite, dolomite, clay, iron oxides or other <br />materials. <br />Dolomite Afine-grained carbonate rock consisting of the mineral dolomite [CaMg(C03)2]. <br />May contain noncarbonate impurities such as quartz, chert, clay minerals, organic <br />matter, gypsum and sulfides. Reacts with hydrochloric acid (HCL). <br />Limestone Afine-grained carbonate rock consisting of the mineral calcite (CaC03). May <br />contain noncarbonate impurities such as quartz, chert, clay minerals, organic <br />matter, gypsum and sulfides. Reacts with hydrochloric acid (HCL). <br />Sandstone Rock consisting of particles of sand with or without interstitial and cementing <br />materials. The cementing or interstitial material may be quartz, opal, calcite, <br />dolomite, clay, iron oxides or other material. <br />Shale Fihe-grained rock composed of or derived by erosion of silts and clays or any <br />rock containing clay. Shale is hard, platy, of fissile may be gray, black, reddish or <br />green and may contain some carbonate minerals (calcareous shale). <br />Siltstone Fine grained rock composed of or derived by erosion of silts or rock containing <br />silt. Siltstones consist predominantly of silt sized particles (0.0625 to 0.002 mm in <br />diameter) and are intermediate rocks between claystones and sandstones and <br />may contain carbonate minerals. <br /> <br />