Transcript Extrusive (volcanic) igneous rocks LAVA IS MOLTEN ROCK THAT

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A ROCK IS A GROUP OF MINERALS
BOUND TOGETHER IN SOME WAY.
ROCKS ARE DIVIDED INTO THREE
GROUPS BASED ON HOW THE
ROCKS FORMED
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IGNEOUS ROCKS ARE FORMED BY THE
COOLING AND HARDENING OF
MOLTEN ROCKS.
INTRUSIVE (PLUTONIC) - FORM
BELOW THE EARTH’S SURFACE
EXTRUSIVE (VOLCANIC) – FORM
ABOVE THE EARTH’S SURFACE
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THERE ARE TWO PHYSICAL PROPERTIES
OF IGNEOUS ROCKS USED IN THE
IDENTIFICATION OF THE ROCK NAME.
TEXTURE REFERS TO THE SIZE
OF THE CRYSTALS IN AN
IGNEOUS ROCK
**THE LARGER THE CRYSTAL SIZE THE
DEEPER WITHIN THE EARTH THE
ROCK FORMED www.oiexploration.ir
COLOR REFERS TO THE MINERAL
COMPOSITION OF THE ROCK.
IT IS IDENTIFIED BY USING THE
GENERAL SHADE OF THE ROCK.
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- IF THERE ARE MORE
LIGHT MINERALS THAN
IT IS LIGHT
- IF THERE ARE MORE
DARK MINERALS THAN
IT IS DARK
- IF THERE IS THE SAME
AMOUNT OF DARK
MINERALS AS LIGHT
THAN IT IS MEDIUM
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Intrusive (plutonic) Igneous Rocks
MAGMA IS MOLTEN ROCK UNDERNEATH THE
EARTH’S SURFACE.
INTRUSIVE IGNEOUS ROCKS COOL SLOWLY
DEEP WITHIN THE EARTH AND PRODUCES
LARGE CRYSTALS
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INTRUSIVE IGNEOUS ROCKS WILL RESULT IN A
VERY COARSE (PEGMATITE) OR COARSE
(PHANERITIC) TEXTURE (EX. GRANITE)
PEGMATITE
GRANITE
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Extrusive (volcanic) igneous rocks
LAVA IS MOLTEN ROCK THAT POURS OUT
ONTO THE EARTH’S SURFACE.
EXTRUSIVE ROCKS LACK DISTINCT
MINERAL GRAINS DUE TO RAPID COOLING
OF LAVA AT OR NEAR THE EARTH’S
SURFACE
EXTRUSIVE IGNEOUS
ROCKS WILL RESULT
IN FINE (APHANITIC)
TEXTURE (EX. BASALT)
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IF THE COOLING IS INSTANTANEOUS A GLASSY
TEXTURE MAY FORM (EX. OBSIDIAN)
IF GAS BUBBLES ARE TRAPPED AS THE LAVA
RAPIDLY COOLS A VESICULAR TEXTURE MAY
OCCUR (PUMICE)
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PORPHYRITIC ROCKS
- CONTAINS TWO STAGES OF COOLING
- COOLS FIRST AT GREAT DEPTH
FORMING LARGE CRYSTALS STILL
SURROUNDED BY MAGMA
- IT IS THEN RUSHED TO THE SURFACE
AND THE REMAINING LIQUID AROUND
IT COOLS QUICKLY FORMING FINEGRAINED CRYSTALS
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GRANITE- QUARTZ, ORTHOCLASE FELDSPAR,
AND AT LEAST ONE OTHER MINERAL; LIGHTCOLORED; COARSE-GRAINED; MAKES UP
CONTINENTS; FELSIC
RYOLITE- FINE-GRAINED GRANITE; FELSIC
OBSIDIAN- VOLCANIC GLASS; RAPID
COOLING; PYROCLASTIC; FELSIC
PUMICE- SPONGE-LIKE BECAUSE OF
ESCAPING AIR BUBBLES DURING COOLING;
FELSIC
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BASALT- FINE-GRAINED; DARK-COLORED;
MAKES UP THE OCEAN FLOOR; MAFIC
GABBRO- COARSE-GRAINED BASALT; MAFIC
DIABASE- GRAIN SIZE INBETWEEN BASALT AND
GABBRO; MAFIC
BASALT GLASS- MAFIC OBSIDIAN
SCORIA- MAFIC PUMICE
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