Geology Test #2
phaneritic
-coarse -can see
andesite in the cascades is produced by melting
a mixture of ocean and continental crust
In geology, a mineral is defined as:
a naturally occurring inorganic solid consisting of chemical elements in specific proportions arranged in specific crystalline pattern
Mineral
a naturally occurring, inorganic solid that has a crystal structure and a definite chemical composition
aphanitic
finely grained can't see glasssy
which texture results from a single, long period of cooling and crystallization
phaneritic
the plate tectonic explanation of volcanic activity in the cascades is
subduction zone
Fracture refers to the way a mineral breaks along flat planes of weakness in the crystalline structure
False
Quartz is the hardest known mineral thus it is nearly impossible to scratch it
False
most volcanoes are composed of basalt or andesite, but not granite (t/f)
TRUE
Aphanitic igneous rocks have mineral grains too small to be seen without magnification
True
Shield volcanoes are commonly composed of basaltic rocks
True
Specific gravity of minerals is the density relative to water (T/F)
True
Silicate
a member of the mineral group that has silicon and oxygen in its crystal structure
rock formed from lava with numerous gas bubbles that give it a jagged surface is
a'a
volcanic rocks are typically
a. intrusive b.coarse grained igneous rocks c. both a and b d. none of the above D
which igneous texture results from a short period of cooling and crystallization
aphanitic
most of the igneous rocks in hawaii are
basalt
if a mineral exhibits it
breaks consistently along distinct flat planes
a small volcano made up of small rock fragments blasted out of a central vent is
cinder cone
which of the following statements about mineral identification is NOT true
color is one of the most reliable ways by which minerals can be identified
the highest volcanic peaks in the cascades are
composite cones
mafic minerals have which properties
dark color, above average specific gravity
pillow lava
erupts under water
volcanic rocks are typically
extrusive igneous rocks
crater lake, orgeon was formed in 1980 when mt mazama volcano erupted
false
Most lava crystallizes to form igneous rocks with phaneritic textures.
false- it creates aphaneritic textures which are glassy fine grained
the gentlest least catastrophic type of volcano eruption occurs when magma is so fluid that it simply oozes from cracks to form
flood basalts
the primary difference between lava and magma is
lava is above ground surface magma is below ground surface
the plate tectonic explanation of volcanic activity is hawaii is
mantle plume and hot spot
the most recent major volcanic eruption is in the cascades was at
mount st.helens
which two minerals are very hard
quartz and diamond
the largest volcano in the Hawaiian islands are
shield volcanoes
mount rainer in washington was formed primarily by
subduction zone volcanics
two properties most used to classify igneous rocks are
texture and mineral composition
mohs hardness scale for minerals refers to
the resistance of a mineral to scratching
columnar joints form from contraction during the cooling of volcanic rocks
true
mount st helens in washington cascades is a classic example of volcanic activity near a subduction zone
true
the glassy texture in obsidian forms when lava cools very quickly
true
the hawaiian islands are long chain of volcanic islands that formed over millions of years as the pacific plate moved northwest over a relatively stationary mantle plume
true
