make a dichotomous key using these rocks:
rhyolite
granite
andesite
diorite
basalt
gabbro
peridotite
obsidian
scoria
pumice
tuff
sandstone
shale
conglomerate
coal
halite
gypsum
chert
coquina
slate
mica schist
gneiss
marble
quartzite
Phyllis
migmatite
rhyolite
granite
andesite
diorite
basalt
gabbro
peridotite
obsidian
scoria
pumice
tuff
sandstone
shale
conglomerate
coal
halite
gypsum
chert
coquina
slate
mica schist
gneiss
marble
quartzite
Phyllis
migmatite