Classifying Rocks - Hicksville Public Schools / Homepage

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Transcript Classifying Rocks - Hicksville Public Schools / Homepage

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.144-147.
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 rock’s 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 rock’s 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: appearance and feel of the rock’s 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.
Grain Shape: Angular/Subangular/Subrounded/Rounded
Grain Pattern:
Grains randomly arranged
Grains of different colors in bands
Grains forming a swirling pattern.
Crystals randomly arranged
Grains aligned in flat, wavy layers
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]