Rocks For Jocks Lab Exam 1
Siliclastic Sedimentary Rocks
Sedimentary rock composed of sand or clay fragments
clastic sedimentary rock
Sedimentary rock made of pieces of other rocks
calcite and dolomite
minerals that react with HCl
plutonic/intrustive
magma cooled below surface
diamagnetic
minerals with no magnetic attraction
fingernail
mohs hardness 2.5
glass scratch plates
mohs hardness 5.0
streak plates
mohs hardness 6.5
Peridotite
A coarse-grained ultramafic rock. Green because it is more than 40% olivine.
conchoidal fracture
A curved mineral fracture surface; looks like the inside of a clam shell
porphyritic texture
A course grained igneous rock texture in which large crystals are scattered on a background of much smaller crystals
phaneritic texture
A course grained igneous rock texture in which minerals mineral crystals are visible, cooled very slowly beneath surface
aphanitic texture
A fine-grained texture of igneous rocks in which mineral crystals exist but are not visible to naked eye, cooled slowly above surface
hardness
A measure of how easily a mineral can be scratched, reliable diagnostic property
metallic
A mineral that has a shiny surface like metal
phosphorescence
A mineral that remains glowing after being exposed to ultraviolet light and then placed in the dark exhibits
Mohs hardness scale
A scale ranking ten minerals from softest to hardest; used in testing the hardness of minerals
silky luster
A silk-like luster, found in minerals with fine, parallel, fibrous bands
Foliation
An arrangement of minerals in metamorphic rocks in flat or wavy parallel bands, caused by directed pressure
pyroclastic texture
An igneous rock with a fragmental texture
Criteria of a mineral: Composition
Chemically homogenous, always definite chemical proportions
Exfoliation
Form of mechanical weathering in sedimentary rocks, decrease in pressure results in expansion
Earthy Fracture
Fracture of minerals that crumble when broken.
Granoblastic
Metamorphic texture, caused by applying only heat, visible equidimensional crystals with random orientations
phyllitic texture
Metamorphic texture, caused by applying heat heat and pressure, has foliation and tiny, fine-grained minerals
Hornfelsic
Metamorphic texture, caused by applying only heat, fine equidimensional crystals with random orientations
splintery fracture
Mineral fracture that forms elongated splinters.
Vitreous luster
Mineral that resembles glass, reflects light like a window pane
Dull/Earthy Luster
Minerals that have a dull appearance like soil
waxy luster
Minerals that have the appearance of candle wax
Criteria of a mineral: Form
Must be a solid at earth's surface temperature
Criteria of a mineral: Type
Must be naturally occurring inorganic (Except fossils)
fracture
The way a mineral looks when it breaks apart in an irregular way/does not have cleavage, reliable diagnostic property
Luster
The way a mineral reflects light, reliable diagnostic property
Hydrolysis
Type of chemical weathering in sedimentary rocks, replaces cations in silicate structures with H+ ions
Dissolution
Type of chemical weathering in sedimentary rocks, salts and carbonates dissolve in water
Oxidation
Type of chemical weathering, minerals with an iron content react with oxygen to form oxides
Ultramafic
Type of magma, highest SiO2, composed mainly of iron and magnesium-rich minerals, tend to have a lot of olivine
Mafic
Type of magma, ~50% SiO2, mostly dark colored minerals
Intermediate
Type of magma, ~60% SiO2, mix of light and dark colored minerals
Felsic
Type of magma, ~70% SiO2, mostly light-colored minerals
Color
Used to identify minerals, sometimes not a reliable diagnostic tool
Criteria of a mineral: Structure
Will always form a crystalline structure given enough space and time, always has an ordered atomic structure
vesicular texture
an igneous rock with a spongy appearance
Clasts
broken pieces and fragments of rock found in sedimentary rocks
Sorting
consistency of particle size in sedimentary rock, tells degree sediments were moved by water
Rounding
degree to which particles in sedimentary rocks have their sharp corners worn away
granite and rhyolite
felsic igneous rocks, compositional twins
gneissic banding
foliation causing alternating layers or lenses of light and dark medium to coarse grained minerals in metamorphic rocks
diamond
hardest mineral on mohs hardness scale
Diorite and Andesite
intermediate igneous rocks, compositional twins
volcanic/extrusive
lava cooled above surface
gabbro and basalt
mafic igneous rocks, compositional twins
3 types of magma composition
mafic, intermediate, felsic
Idiochromatic
mineral always same color
allochromatic
mineral colored by impurities, may be different colors
obsidian
mineral commonly known for its conchoidal fracture pattern
Tenebrescence
mineral that changes color under ultraviolet light but reverts back over time.
Pearly luster
mineral that looks like a pearl
ferromagnetic
mineral with strong magnetic properties
paramagnetic
minerals that are weakly magnetic
fluorescence
minerals that glow under ultraviolet light
bioclastic sedimentary rocks
sedimentary rock composed of broken shell fragments or similar remains of living organisms
Limestone
sedimentary rock that reacts to HCl
Volcaniclastic Sedimentary Rocks
sedimentary volcanic rock consisting of fragments of older rocks
talc
softest mineral on Mohs hardness scale
streak
the color of a mineral's powder, reliable diagnostic property
metamorphic grade
the degree to which the parent rock changes during metamorphism
Bowen's Reaction Series
the simplified pattern that illustrates the order in which minerals crystallize from cooling magma according to their chemical composition and melting point
cleavage
the tendency of a mineral to break along smooth, flat surfaces and parallel planes, reliable diagnostic property
habit/form
way a mineral has a propensity to grow, reliable diagnostic property