Rock Identification Exam 2

Pumice

-Igneous

-volcanic

-vesicular

-Intermediate/felsic

-made up of light minerals

-formed last in Bowens reaction series

Uses: abrasives

Diorite

-Igneous

-plutonic

-porphyritic/pegmatatic

-intermediate (felsic-mafic)

-Ca/Na plagioclase, pyroxene, hornblende (amphibole)

-formed in the middle of Bowens reaction series

uses: construction

Pegmatite (teeth)

-igneous

-plutonic

-pegmatitic

-felsic

-K-feldspar, quartz, Na-plagioclase

-formed at the end of Bowens reaction series

uses: construction

granite

-igneous

-plutonic

-phoneritic

-felsic

-K-feldspar, quartz, Na-plagioclase

-formed at the low temp extreme of BRS

uses: countertops

Scoria

-igenous

-volcanic

-vesicular

-mafic/intermediate

-made up of dark minerals

-forms at the middle-upper section of BRS

uses: construction

obsidian

-igneous

-volcanic

-glassy

-felsic

-made up of dark minerals

-forms at the end of BRS

uses: jewelry

Basalt

-igneous

-volcanic

-amygdaloidal

-mafic

-Ca-plagioclase, pyroxene, olivine

-forms at beginning of BRS

uses: construction

Gabbro

-igneous

-plutonic

-phaneritic/porphyritic

-mafic

-Ca-plagioclase, pyroxene, olivine, hornblende

-forms at upper-middle of BRS

uses: construction

Andesite

-igneous

-volcanic

-aphanitic, porphyritic, vesicular, amydgoloidal

-intermediate

-Ca/Na plagiocalse, pyroxene, hornblende

-forms in the middle of BRS

uses: construction

Syenite

-igneous

-plutonic

-phaneritic, porphyritic

-felsic

-K-feldspar, Na-plagioclase, quartz

-forms late in BRS

uses: building

basalt

-igenous

-volcanic

-aphanitic, glassy, porphyritic

-mafic

-Ca-plagiclase, pyroxene

-forms at the beginning of BRS

uses: construction

Rhyolite

-igneous

-volcanic

-aphanitic

-felsic

-K-feldspar, quartz, biotite

-forms at the end of BRS

uses: construction

Granite

-igneous

-plutonic

-porphyritic, phaneritic

-felsic

-K-feldspar, quartz, Na-plagioclase

-forms at the low temp extreme of BRS

uses: countertops

Trachyte

-igneous

-volcanic

-porphyritic

-felsic

-Ca-plagioclase, pyroxene

-forms in the middle of BRS

uses: construction/building

Basalt

-igneous

-volcanic

-vesicular

-mafic

-Ca-plagioclase, pyroxene

-forms at beginning of BRS

uses: construction

Tuff

-igneous

-volcanic

-aphanitic, porphyritic

-felsic/intermediate

-volcanic ash, pumice

-doesn’t form within BRS

uses: building

Glassy

Igneous volcanic texture

-No visible grains, smooth, shiny

Vesicular

Igneous volcanic texture

-presence of spherical to elongated holes throughout the rock

Amygdaloidal

igneous volcanic texture

-Filled vesicular texture, where filling consists of other minerals lining or completely filling vesicles

Aphanitic

igneous volcanic texture

-most crystals are visible to the naked eye, some may be big enough to catch the light. Not glassy

Porphyritic

igneous plutonic/volcanic texture

-Crystals of multiple sizes

volcanic rocks - matrix is aphanitic embedded with several mm to cm size larger crystals

plutonic rocks - matrix is phaneritic embedded with several cm size larger crystals

Phaneritic

igneous plutonic textures

-all crystals are visible without magnification and all about the same size

Pegmatitic

All crystals are several cm in size, extremely coarse texture

Mafic

dark colored minerals

felsic

light colored minerals

intermediate

a moderate silica content, falling between the high silica content of felsic rocks and the lower silica content of mafic rocks

Plutonic (intrusive)

rocks are formed from magma cooling and solidifying underground

-large crystals

Volcanic (extrusive)

rocks are formed from lava cooling and solidifying above ground

-small crystals

Quartz Arenite Sandstone

-sedimentary

-clastic

-coarse to fine grain

-poor to well sorted

-sub angular to rounded shape

-quartz

-primary source of quartz arenite is the weathering of rocks containing quartz, such as granites, or other quartz-rich rocks

uses: construction

Quartz Arenite Sandstone

-sedimentary

-clastic

-coarse to fine grain

-poor to well sorted

-sub angular to rounded shape

-quartz

-primary source of quartz arenite is the weathering of rocks containing quartz, such as granites, or other quartz-rich rocks

uses: construction

Arkose Sandstone

-sedimentary

-clastic

-coarse to fine grained

-poorly sorted

-sub-angular to rounded shape

-quartz, K-feldspar

-rapid weathering and erosion of feldspar-rich igneous or metamorphic rocks, particularly granitic rocks

uses: construction

Fossiliferous Limestone

-sedimentary

-biochemical

-shell fragments

-carbonate mud

-will react to HCl

-originates from shallow, warm, marine environments

uses: construction

Oolitic Limestone

-sedimentary

-chemical

-calcite

-will react to HCl

-forms in warm, shallow, agitated marine environments

uses: building

Chert

-sedimentary

-biochemical

-sponges, radiolarien, siliceous diatoms

-quartz

-wont react to HCl

-forms from biogenic silica from marine organisms like radiolarians and diatoms

uses: construction

Shale

-sedimentary

-clastic

-extremely fine grained

-well sorted

-rounded shape

-clay minerals

-forms from compaction of fine-grained mud and clay particles, typically deposited in slow-moving or still water environments

uses: oil and natural gas

Bituminous Coal

-sedimentary

-biochemical

-organic carbon

-wont react to HCl

-forms from the transformation of buried plant material, particularly peat, under high pressure and heat over millions of years

uses: electricity generation

Breccia

-sedimentary

-clastic

-coarse grained

-poorly sorted

-angular to sub-angular shape

-quartz, chert

-forms from processes like landslides, rock avalanches, faulting, volcanic eruptions, or meteorite impacts, resulting in the accumulation of broken rock debris

uses: decorative uses

Siltstone

-sedimentary

-clastic

-fine grained

-well sorted

-unidentifiable shape

-quartz, clay

-forms in relatively quiet depositional environments where silt-sized particles can settle out of moving water or wind and accumulate

uses: construction

Conglomerate

-sedimentary

-clastic

-coarse grained

-poorly sorted

-rounded to subrounded

-quartz, chert

-sediments deposited by fast-moving rivers and streams, or by wave action along beaches, where these clasts are transported and then cemented together over time

uses: construction

Greywacke Sandstone

-sedimentary

-clastic

-fine to med grained

-poorly sorted

-sub-angular to rounded shape

-quartz, clay

-forms from the rapid deposition of mixed sediments, including sand, silt, and rock fragments, in deep ocean environments

uses: construction

Mudstone

-sedimentary

-clastic

-extremely fine grained

-clay minerals

-forms in quiet, low-energy environments like tidal flats, lakes, and the deep sea, where clay particles accumulate and harden over time

uses: construction

Coquina

-sedimentary

-biochemical

-shell fragments

-high porosity

-will react to HCl

-shallow coastal areas, especially in tropical or sub-tropical marine areas

uses: building

Shale

-sedimentary

-clastic

-extremely fine grained

-well sorted

-rounded shape

-clay minerals

-forms from compaction of fine-grained mud and clay particles, typically deposited in slow-moving or still water environments

uses: oil and natural gas

Dolostone

-sedimentary

-biochemical

-visible shell fragments

-calcite

-will react to HCl

-formed by the replacement of pre-existing calcium carbonate sediments (limestone) by magnesium-rich fluids, a process called dolomitization, often occurring in ancient marine environments

uses: construction

Clastic

rocks composed of broken pieces of older rocks

Biochemical

those formed through the biological activity of organisms, where they extract chemicals from their environment to build their skeletons or body parts, which then accumulate and lithify into rock

-May react to HCl

chemical

formed through the chemical precipitation of minerals from water solutions, resulting in the accumulation and subsequent compaction of these mineral grains

-reacts to HCL

Slate

-metamorphic

-foliated

-slaty

-red slate

proliths: shale or mudstone

-regional metamorphism - low>med>high grade

uses: construction

Phyllite

-metamorphic

-foliated

-phyllitic

-amphibole, Ca-plagioclase, quartz

proliths: shale or mudstone

regional metamorphism - low>med>high grade

uses: decorative applications

Biotite Schist

-metamorphic

-foliated

-Schistose

-biotite, muscovite, feldspar

proliths: shale or mudstone

regional metamorphism - low>med>high grade

uses: decorative applications

Muscovite Schist

-metamorphic

-foliated

-schistose

-muscovite, quartz

proliths: shale or mudstone

regional metamorphism - low>med>high grade

uses: building

Marble

-metamorphic

-nonfoliated

-crystalline

-calcite, quartz, feldspar

proliths: limestone or dolostone

regional metamorphism - med grade

uses: construction

Granite Gneiss

-metamorphic

-foliated

-gneissic

-Na-plagioclase feldspar, biotite, hornblende

proliths: felsic, intermediate plutonic rocks

regional metamorphism - high grade

uses: construction

Feldspar Gneiss

-metamorphic

-foliated

-gneissic

-K feldspar, plagioclase feldspar, hornblende, quartz

proliths: felsic or int. plutonic rocks, granite, diorite

Regional metamorphism - high grade

uses: construction

Quartzite

-metamorphic

-nonfoliated

-micro-crystalline

-quartz, micas

proliths: sandstone

regional metamorphism - high grade

uses: countertops

Feldspar Gneiss

-metamorphic

-foliated

-striations

-gneissic

-feldspar, hornblende

proliths: felsic or int. plutonic rocks, granite, diorite

regional metamorphism - high grade

uses: construction

Amphibole Schist

-metamorphic

-foliated

-shistose

-amphibole (hornblende)

proliths: mafic igneous rocks (basalt, gabbro)

regional metamorphism - low>med>high grade

uses: construction

Anthracite Coal

-metamorphic

-nonfoliated

-micro-crystalline

-carbon

proliths: bituminous coal

regional or contact metamorphism - low grade

uses: heating systems

Green Schist

-metamorphic

-foliated

-schistose

-chlorite, biotite, schist

proliths: mafic volcanic/plutonic rocks, basalt, gabbro

regional metamorphism - low grade

uses: decorative purposes

Gray Slate

-metamorphic

-foliated

-slaty

-amphibole

proliths: shale or mudstone

regional metamorphism - low>med>high

uses: roofing

Eclogite

-metamorphic

-nonfoliated

-crystalline

-garnet, pyroxene, quartz

-proliths: mafic volcanic, plutonic rocks, gabbro, basalt

regional metamorphism - high grade

uses: geologic research

Amphibolite (schist/gneiss)

-metamorphic

-foliated

-shistose/gneissic

-amphibole, quartz

proliths: mafic volcanic, plutonic rocks, basalt, gabbro

regional metamorphism - high grade

uses: construction

Serpentinite

-metamorphic

-nonfolliated

-serpentine, quartz

proliths: ultramafic plutonic rocks, peridotite

regional metamorphism - med grade

uses: decorative architecture

Slaty

No visible grains, dull luster, well developed cleavage surfaces along which rocks splits into flat sheets/tiles

Phyllitic

No visible grains, satin/polished luster, foliation is distinctly wavy

Schistose

Visibly platy minerals (sparkly mm-size to large cm-size crystals) along wavy foliation planes. Shiny rock commonly containing other large visible crystals

gneissic

Distinct banding with alternating bands of different minerals. (usually light and dark alternating bands, sometimes banding may only contain one prominent mineral). Micas may be present but do not dominate the foliation as in schists

Foliated

metamorphic rocks that exhibit a layered or striped appearance due to the parallel alignment of mineral grains, often caused by pressure or heat during metamorphism

Non-foliated

lack a layered or banded appearance, unlike foliated rocks, and are characterized by a more uniform texture due to the recrystallization of minerals without directional pressure