Igneous Sedimentary and Metamorphic Rock ID Charts Some Common Rock Forming Minerals Harder or Cleavage Color Softer Than breaks along planes Glass Harder No variable Harder Yes Harder No Harder No Harder Yes Similar Yes Similar Yes Similar Yes Softer Yes Softer Yes Softer Yes Softer Yes Other Properties glassy luster conchoidal fracture breaks like glass peach pink to glassy luster banding 2 cleavages at 90 white also called potassium feldspar olive green glassy luster granular weathers brown orange red to brown twelve sided or spherical common glassy luster pistachio surface coatings or massive green white to gray glassy luster 2 cleavages at 90 striations grooves possible on cleavage faces white sodium rich dark calcium rich dark green to glassy to dull luster 2 poor cleavages at 90 black dark green to glassy luster splintery appearance 2 black cleavages at 120 and 60 clear to light glassy luster perfect cleavage in 1 dir yellow forms flexible transparent thin sheets brown to glassy luster perfect cleavage in 1 direction black forms flexible thin sheets white to clear reacts with hydrochloric acid HCl glassy darker if to dull luster 3 cleavages not at 90 to each massive other white to clear salty taste glassy to dull luster 3 cleavages at 90 to each other breaks into cubes MINERAL NAME QUARTZ ORTHOCLASE Pink Feldspar OLIVINE GARNET EPIDOTE PLAGIOCLASE White to Dark Grey Feldspar PYROXENE AMPHIBOLE MUSCOVITE clear mica BIOTITE black mica CALCITE HALITE Igneous Rock Names Felsic COMPOSITIONS Minerals Present are in columns Intermediate Mafic Quartz Pink feldspar White feldspar Grey feldspar White feldspar Black amphibole Dark pyroxene Black mica Black mica Olivine Clear mica TEXTURES are in rows Coarse grained GRANITE DIORITE GABBRO Fine grained RHYOLITE ANDESITE BASALT Sedimentary Rock Names GRAIN SIZE Coarse grained pebble cobble boulder Medium grained sand Fine grained silt Very fine grained OTHER PROPERTIES Rounded grains Angular grains Sand sized particles ROCK NAME CONGLOMERATE BRECCIA SANDSTONE Feels gritty on teeth or between fingers SILTSTONE Feels smooth soft often layered clay Harder denser fizzes in dilute acid calcite SHALE LIMESTONE Metamorphic Rock Names FOLIATED LAYERED Yes slaty cleavage breaks into flat plates Yes schistosity platy foliation of mica grains Yes gneissic light and dark banding Yes aggregate of long amphibole crystals No made of quartz PROTOLITH OTHER PROPERTIES used to be this kind of rock Microscopic to very fine grained clay Shale minerals common cleavage surfaces dull to slightly shiny Medium to coarse grained mica minerals Shale siltstone common may also contain garnets Medium to coarse grained mostly nonmicas light and dark layers common Dark green to black also may contain black mica feldpars and or garnets Shale siltstone granite Basalt gabbro ROCK NAME SLATE SCHIST GNEISS AMPHIBOLITE Fine to coarse grained crystalline texture Quartz sandstone QUARTZITE light colored scratches glass No made of calcite Commonly coarsely crystalline reacts Limestone MARBLE with acid usually light colored does not scratch glass No made of rock Coarse grained sometimes deformed Conglomerate METACONGLOMERATE fragments rock fragments rock breaks through individual clasts