1 Fossils are present. 100% 5 Sedimentary Clastic, Biochemical, or Organic Layers are present. 99% Examine the sample to determine whether the layers are beds (sedimentary), colour banding from foliation (metamorphic) or rock cleavage (metamorphic). Examine the texture, grain size, mineral composition, and colour to determine which specific kind of these three sedimentary rock types it is. 2 Garnet is present. 100% 6 Metamorphic Foliated OR Examine the texture, grain size, and rock cleavage to determine which foliated metamorphic rock it is. 3 Foliation is present. 100% ! 4 99% 95% Sedimentary or Metamorphic Exception: Igneous rocks can have small amounts of calcite in veins and filling vesicles. 70% Glitters Examine the mineral composition to determine which non-foliated metamorphic rock it is. Some coarse-grained clastic sedimentary rocks have clasts aligned by flowing water and could resemble metaconglomerate. Look for foliation throughout, not just in the arrangement of clasts.. Igneous Mafic or Ultramafic Exception: Some metamorphic rocks where chemical reactions with olivine in an igneous protolith are incomplete. Examine the texture and composition to determine which mafic or ultramafic rock it is. OR Look for evidence of flat crystal faces, semi-transparent crystals, & uniform composition to confirm that it is marble. 7 Examine the texture, grain size, and rock cleavage to determine which foliated metamorphic rock it is. Olivine is present. Calcite is present. Non-Foliated Metamorphic Sedimentary or Metamorphic 8 A crystalline rock has some well-formed crystals that are much larger than other crystals surrounding them. Vesicles or amygdules are present. 90% Doesn’t Glitter Look for a dull lustre, light grey or tan colour, and absence of visible crystals as evidence of limestone. Igneous or Metamorphic In igneous rocks these are phenocrysts. Similar crystals in metamorphic rocks are porphyroclasts or porphyroblasts. Examine the sample for other igneous or metamorphic textures, or minerals that are exclusive to igneous or metamorphic rocks. 100% ! 99% Igneous, Volcanic Some sedimentary rocks have irregularly-shaped openings. Vesicles are openings that resemble bubbles. Lower than average density OR Examine the colour to determine whether the rock is pumice or scoria. Average density Examine the colour, lustre, and look for phenocrysts to determine whether it is rhyolite, andesite, basalt, or obsidian. Karla Panchuk (2017) CC BY 4.0 9 10 Contains rounded or broken fragments that are not fossils. Breaks or crumbles relatively easily. 80% Sedimentary, Clastic, Medium-Coarse Grained Clastic, Biochemical, or Organic 13 Examine the grain size and shape to determine whether the rock is sandstone, conglomerate, or breccia. 80% Weathering and fractures can cause any rock type to break easily. 14 It glitters when turned slightly in the light. Examine the texture and grain size to determine which clastic sedimentary rock it is. 11 3 or more colours 70% 65% Feels Smooth OR Look at the lustre. Obsidian has glassy lustre. Shale can have a dull lustre and makes a knock when you hit it on a surface. Slate can have a soft shine and clink when hit. ! Sedimentary, Clastic Exception: highly vesicular igneous rocks can break or crumble easily. ! Dark with no visible grains. Feels Rough Check if the rock is light for its size. If yes, and vesicles are abundant, it is scoria. If not, basalt. Weathering can make a rough rock feel smooth. 70% Metamorphic, Medium-High Grade or Igneous, Intrusive 80% Tiny sparkles OR Lots of sparkles without colour banding is schist. Fewer sparkes with colour banding is gneiss. Igneous, Felsic or Metamorphic, High Grade Larger flashes Look at the mineral composition to determine what kind of intrusive igneous rock it is. Exception: Some coarse-grained sedimentary rocks could appear multicoloured. ! 100% Do not count colours from secondary features such as veins, staining, or weathering reactions. No pattern OR Examine the grain size to determine whether the rock is granite or porphyritic rhyolite. Colour bands Examine the rock for foliation to confirm that it is gneiss. 15 When the sample is wet then wiped dry, a darker patch remains. 75% ! Sedimentary, Clastic This effect is due to porosity, and can occur in muddy limestones and on some weathered surfaces. Look at the grain size to determine the type of clastic sedimentary rock. Karla Panchuk (2017) CC BY 4.0 12 Feels gritty. 65% ! Sedimentary, Sandstone Whether something feels gritty (like sandpaper) or not is subjective. A rough texture is not necessarily a gritty texture. Examine the grain size and check for the presence of quartz to help confirm that the rock is sandstone.