Phaneritic Sedimentary Rocks (Coarse-Grained)
Classification Chart
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GRAIN SIZE
1/256 to 1/16 mm
(silt)
Feels ever so slightly gritty, like the finest sandpaper
1/16 to 2 mm
(sand)
Feels and looks like medium to coarse sandpaper
> 2 mm
(gravel)
MINERAL CONTENT           ROCK NAME
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C
O
M
P
O
S
I
T
I
O
N

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SCRATCHES
GLASS
(H>5.5)
Predominantly QUARTZ
 SILTSTONE
QUARTZ
ARENITE
QUARTZ PEBBLE
CONGLOMERATE
> 25% FELDSPAR
< 75% QUARTZ
FELDSPATHIC 
WACKE
(Arkose)
FELDSPATHIC
(Arkosic)
CONGLOMERATE
MIXTURE of mineral fragments, rock fragments, and clay and silt
WACKE
(Greywacke)
POLYMICT
CONGLOMERATE
DOES NOT
SCRATCH
GLASS
(H<5.5)
CALCITE, variable color, H=3,  REACTS VIGOROUSLY with HCl (effervesces)
FINE-GRAINED
LIMESTONE
COARSE-GRAINED LIMESTONE
calcite cleavage or large crystals evident

FOSSILIFEROUS LIMESTONE
contains visible fossils

COQUINA
porous, composed of shell fragments, 
looks like GRANOLA BAR

OOLITIC LIMESTONE
composed of sand-sized, spherical beads (ooids)

DOLOMITE, variable color, H=3, REACTS with HCl, but RELUCTANTLY
(may react only in powder form)
FINE-GRAINED
DOLOSTONE
COARSE-GRAINED
DOLOSTONE
GYPSUM, WHITE but sometimes stained by hematite, H=2, NO reaction with HCl
GYPSUM EVAPORITE
HALITE, COLORLESS and clear, or WHITE, H=2.5, TASTES SALTY
 HALITE EVAPORITE
  



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