AIM: What characteristics are used to identify rocks and what are the three main groups of rocks? OBJ: Given notes and activity sheet SWBAT explain the characteristics that are used to identify rocks and the three main groups of rocks with 70% accuracy. DN: Hand-in Minerals Lab write-up and Lab Quiz scantron Distribute Classifying Rocks Activity Sheet ACT: Introduction to Classifying Rocks (notes) Text, read, p iPads (eSpark Assignment) HW: Complete Classifying Rocks Activity Sheet; Work on MR Review Sheets; Mineral & Rocks Exam, March 19. Classifying Rocks Rock Classification is based on: 1)Mineral composition 2) Color 3) Texture 4) How Rock Formed / Origin Mineral Composition & Color Rock: consists of one or more minerals Monomineralic: one mineral only Example: Limestone, Marble (calcite) Rock Salt (halite) Polymineralic: many minerals Example: diorite (quartz, plagioclase, mica) Rock color provides clues to a rocks mineral composition. Light color Rocks: contain high silica content Dark color rocks: contain low silica content; may contain iron, magnesium Carbonate rocks: bubble in acid Grain: mineral/rock particle Grain shape are clues to rocks origin: 1)Rounded grains sedimentary rock angular grains (no twinkle/sparkle) = sedimentary rock fragment 2)Angular grains (twinkle/sparkle = crystals) crystals randomly arranged - igneous rock crystals aligned/oriented metamorphic rock Texture Texture: appearance and feel of the rocks surface. Texture is based on size, shape and pattern of the grains. Grain Size: Coarse: large grains; seen using eyes Fine: small grains; seen using microscope Glassy: amorphous, no grains seen. Texture Grain Shape: Angular/Subangular/Subrounded/Rounded Texture Grain Pattern: Grains randomly arranged Crystals randomly arranged Grains of different colors in bands Grains aligned in flat, wavy layers Grains forming a swirling pattern. How Rock Formed (Origin) Rocks are classified into three major groups: Igneous: form from the cooling and solidification of magma or lava [ volcano setting] Sedimentary: form when rock particles or plant/animal remains undergo compaction and/or cementation. [ water (river, wave, ocean, lake, glacial) & wind (desert) setting] Metamorphic: form when existing rock undergoes heat & pressure or chemical reaction deep underground. [ mountain-building setting by plate collision]