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.i <br />.i <br />.I <br />.~ <br />.~ <br />.~ <br />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 of pre-existing rocks derived by mechanical weathering, evaporation or by <br />chemical or organic origin. The sediments are usually indurated by cementation ur compaction. <br />Chert Very fine-grained siliceous rock composed of micro-crystalline or crypto- <br />crystalline quartz, chalcedony or opal. Chert is various col~~red, porous to <br />dense, hard and 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; gray, black, brown, reddish or green and <br />may contain carbonate minerals. <br />Conglomerate Rock consisting of a considerable amount of rounded gravel, send and cobbles <br />with or without interstitial or cementing material. The cementi~ig 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 mines{ d~~lomite iCaMg <br />(CO~)Z]. May contain noncarbonate impurities such as quaiYZ, chert, clay <br />minerals, organic matter, gypsum and sulfides. Reacts with hydrochloric acid <br />(HCL). <br />Limestone Afine-grained carbonate rock consisting of the mineral calcite (CaCo~l. May <br />contain noncarbonate impurities such as quartz, chert, clay minerals, organic <br />matter, gypsum and sulfides. Reacts with hydrochloric acid 1HCL1• <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 Fine-grained rock composed of, or derived by erosion of silts and clays or any <br />rock containing clay. Shale is hard, platy, or fissile may be gray, black, <br />reddish or green and may contain some carbonate minerals (calt:areous shale). <br />Siltstone Fine grained rock composed of, or derived by erosion of silts or rock <br />containing silt. Siltstones consist predominantly of silt sized particles (0.0625 <br />to 0.002 mm in diameter) and are intermediate rocks between <:laystones and <br />sandstones, may be gray, black, brown, reddish or green anci may contain <br />carbonate minerals. <br />Empire LaboratoriE~s, Inc. <br />A Divicinn of ThP Torra~nn f:mm~anioe Inr.. <br />,~ <br />