GEOL 20 sedimentary rocks + minerals quiz edited

CLASTIC/DETRITAL

GRAIN:

size— <1/256mm, shape— very fine, sorting— well-sorted

HCI: NO reaction

ENVIRONMENT: continental to marine

CEMENT: calcite

POROUS: yes

MINERAL(S): mostly clay, quartz, feldspars
OTHER: splits easily, feels chalky-to-smooth

Shale (mudstone)

CHEMICAL/BIOCHEM

GRAIN:

size— 1 - 4mm, shape— “chunky”, granola-like, sorting— poorly-sorted

HCI: reaction

CEMENT: calcite

POROUS: yes

MINERAL(S): calcium (shell fragments)

ENVIRONMENT: marine (shallow reef)
OTHER: looks like oats, made almost entirely of shell fragments

Coquina (shells)

CHEMICAL/BIOCHEM

GRAIN:

size— ranges from 1/16 - 2mm, shape— very fine to very coarse, sorting— well-sorted

ENVIRONMENT: continental to intermediate marine

HCI: reaction

CEMENT: well-cemented, “coarsely crystalline”

POROUS: no

MINERAL(S): calcium carbonate
OTHER: waxy

Limestone

CLASITIC/DETRITAL

GRAIN:

size— 1/16mm - 2mm, shape— coarse angular grains, sorting— poorly-sorted

HCI: reaction

ENVIRONMENT: continental (alluvial fan)

CEMENT: calcite

POROUS: yes

MINERAL(S): quartz, feldspar, rock and/or clay
OTHER: feels gritty or sandy, variable grain size

Arkose (feldspar sandstone)

CHEMICAL/BIOCHEM

GRAIN:

size— <1/256mm - 1/8mm, shape— very fine, sorting— well-sorted

HCI: reaction

ENVIRONMENT: intermediate marine (continental slope/rise)

CEMENT: poorly-cemented by calcite

POROUS: yes

MINERAL(S): calcium, clay minerals

ENVIRONMENT: intermediate marine (continental slope/rise)
OTHER: very soft and light earthy rock, white to light brown

Chalk (soft, important)

CHEMICAL/BIOCHEM

GRAIN:

size— micro-crystalline, shape— conchoidal fracture, sorting— well-sorted

HCI: NO reaction’

ENVIRONMENT: deep marine (abyssal plain)

CEMENT: silica

POROUS: low

MINERAL(S): quartz, chalcedony, flint, opal, etc.
OTHER: scratches glass, hard and waxy feel

Chert (scratches glass! important)

CLASTIC/DETRITAL

GRAIN:

size— 1/256mm - 1/16mm, shape— very fine, sorting— well-sorted

HCI: likely reaction

ENVIRONMENT: continental (lake) to marine (continental slope/rise)

CEMENT: calcite

POROUS: low

MINERAL(S): quartz, feldspar, rock and/or clay fragments
OTHER: feels chalky, does not split along layers (non-fissile)

Siltstone (reminds me of rhyolite +HCl)

CHEMICAL/BIOCHEM

GRAIN:

size— <1/256mm - 1mm, shape— very fine, sorting— poorly-sorted

HCI: NO reaction CEMENT: poorly-cemented POROUS: yes

ENVIRONMENT: deep marine (abyssal plain)

MINERAL(S): fossilized diatoms, quartz, chalcedony, flint, opal, etc.
OTHER: very soft and light earthy rock, white to light brown, similar to chalk

Diatomite (no HCl reaction! white like chalk)

CLASTIC/DETRITAL

GRAIN:

size— >2mm gravel, shape— rounded grains, sorting— poorly-sorted

HCI: reaction

ENVIRONMENT: continental (river/stream channel)

CEMENT: calcite

POROUS: yes

MINERAL(S): quartz, feldspar, rock and/or clay minerals

OTHER: very chunky, generally poorly sorted fragments

Conglomerate (massive gravel pieces)

CLASTIC/DETRITAL

GRAIN:

size— >2mm, shape— angular grains, sorting— poorly-sorted

HCI: NO reaction

ENVIRONMENT: continental (alluvial fan)

CEMENT: calcite

POROUS: yes

MINERAL(S): quartz, feldspar, rock and/or clay minerals
OTHER: very chunky like conglomerate but sharper/more angular, generally poorly sorted fragments

Breccia (sharper than conglomerate)

CLASTIC/DETRITAL

GRAIN:

size— 1/16mm - 2mm, shape— gritty/sandy, sorting— well-sorted

HCI: NO reaction

CEMENT: quartz

ENVIRONMENT: continental (river/stream channel)

POROUS: yes

MINERAL(S): quartz, feldspar, rock and/or clay fragments
OTHER: asymmetrical ripplemarks

Quartz sandstone (very smoooooooth)

CHEMICAL/BIOCHEM:

GRAIN:

size— crystalline to micro-crystalline, shape— coarse fossils, sorting— poorly-sorted

ENVIRONMENT: marine (shallow reef)

HCI: reaction

CEMENT: well-cemented

POROUS: yes

MINERAL(S): calcite
OTHER: fossils present

Fossliferous limestone (looks like shells kinda, reef environ)

CLASTIC/DETRITAL:

GRAIN:

size— 1/16mm - 2mm, shape— gritty/sandy, sorting— poorly-sorted

ENVIRONMENT: marine (shallow inner shelf)

HCI: reaction

CEMENT: well-cemented, calcite

POROUS: yes

MINERAL(S): quartz, feldspar, rock and/or clay minerals
OTHER: fossils present

Fossiliferous sandstone

CLASTIC/DETRITAL:

GRAIN:

size— 1/16mm - 2mm, shape— uniform grain, sorting— poorly-sorted

ENVIRONMENT: marine (continental slope/rise)

HCI: possibly

CEMENT: well-cemented

POROUS: low

MINERAL(S): quartz, feldspar, rock and/or clay minerals
OTHER: angular grains

Graywacke

Formula: CaCO₃

Color: Typically colorless or creamy white - may have shades of brownish colors

Solubility: Soluble in dilute acids

Category: Carbonate mineral

Cleavage: Perfect on, three directions with angle of 74° 55'

calcite

Alabaster: Fine-grained, slightly colored

Category: Sulfate minerals

Formula: CaSO₄·2H₂O

Fracture: Conchoidal fracture, splintery parallel

Luster: Vitreous to silky, pearly, or waxy

gypsum

Cleavage: Perfect, three directions cubic

Crystal habit: Predominantly cubes and in massive sedimentary beds, but also granular, fibrous and compact

Crystal system: Cubic

Formula: NaCl

Fracture: Conchoidal

Luster: Vitreous

Halite (see thru ish)

Colors: Green, Blue, Purple, Black, Pink, Yellow, Red, White, Orange, Brown

Chemical formula: CaF₂

Hardness (Mohs hardness scale): ≥ 4

Luster: Vitreous

Refractive index: ≥ 0.434

Transparency: Transparent, Translucent

Cleavage: Octahedral, perfect on, parting on

Fluorite (colors + octahedral!!)

Colors: Blue, Green, Red, White, Black, Pink, Yellow, Purple, Orange, Grey, Brown

Hardness (Mohs hardness scale): 6.5 – 7

Chemical formula: SiO₂

Luster: Vitreous, Waxy

Category: Tectosilicate minerals, quartz group

Cleavage: Absent

Chalcedony (no cleavage, hard, almost waxy)

Sulfur

Graphite

Hardness: less than 1! very soft

Vitreous and waxy looking

Talc

Hardness: 6.5-7ish

Cleavage: Indistinct

Color: virtually all colors, blue is rare, known for reds

Crystal system: Isometric

Fracture: conchoidal to uneven

Cleavages: Dodecahedral cleavages

Garnet