Rock and Mineral identification

Quartz - crystal

Mineral

Color: several possible, often white, clear, or pink

Streak: colorless or light colored

Layers:

Texture: smooth

Shiny: glassy luster in crystal form

Hardness: Moh's scale 7

Other: hexagonal shape fracture (crystals)

specific gravity: 2.65

Calcite - Iceland spar

Mineral

Color: white/clear

Streak:

Layers:

Texture:

Shiny:

Hardness:

Other:

reacts to acid

rhomohedral crystals

shows a double image

Copper

Mineral

Color: copper red-orange (blue/green patina, like rust)

Streak: copper red-orange

Layers:

Texture:

Shiny: metallic luster

Hardness:

Other: bendable and conducts heat and electricity

used to make wires

when exposed to acid, it forms a blue-green patina.

special forms: Float and denrytic

Galena

Mineral

Color: gray

Streak: gray

Layers: breaks into cubes

Texture:

Shiny: metallic luster

Hardness: Moh's scale 2.5

Other: high specific gravity (feels heavy for size)

perfect cubic cleavage, most common lead ore

Used in making crystal radios

Exposure to acid causes a smell like rotten eggs!

Pyrite

Mineral

Color: brassy yellow

Streak: greenish-black

Layers:

Texture:

Shiny: shiny metallic

Hardness: Moh's scale 6

Other:

Looks like gold, also called "fools' gold"

Feldspar

Mineral

Color: White/pink

Streak: colorless or white

Layers:

Texture:

Shiny: glassy to pearly

Hardness: Moh's scale 6

Other:

Specific gravity 2.55

looks like marble

most common mineral on earth

harder than feldspar

Mica-Biotite

(top black piece)

Mineral

Color: brown/black

Streak:

Layers: yes, flakes in thin sheets. It has perfect cleavage in one direction.

Texture: smooth

Shiny: glassy

Hardness: Moh's scale 2.5-3, can be scratched by a fingernail

Other:

nonmetalic

type of mica

Can be used in insulation

Color is caused by biologic materials exposed to oxygen as it cools.

Halite

Mineral AND a rock

Color: white, red or blue

Streak: white

Layers:

Texture:

Shiny: glassy (vitreous)

Hardness: Moh's scale 2.5

Other:

salty, used for cooking and for road safety

Perfect cubic cleavage

forms when moisture evaporates

Granite

Intrusive Igneous Rock

Color: varies, but often speckled gray, black, white or pink

Streak:

Layers: no

Texture: big crystals

Shiny: may have shiny flecks but has dull areas too

Hardness:

Other: often used for construction of buildings and monuments, polished for tile and countertops

Basalt

(dark rocks)

Extrusive Igneous Rock

Color: black or dark

Streak:

Layers:

Texture: little crystals

Shiny:

Hardness:

Other:

Scoria

Extrusive Igneous Rock

Color: medium to dark

Streak:

Layers:

Texture: full of different sizes of air bubbles

Shiny: dull

Hardness:

Other: DOES NOT float in water

AKA - "Lava rock" often used in landscaping

similar to pumice, but cooled more slowly

Obsidian

Extrusive Igneous Rock

Color: black

Streak: none

Layers:

Texture: very smooth

Shiny: glassy

Hardness:

Other: formed from lava, known as "nature's glass"

Sandstone

Sedimentary Rock

Color:

Streak:

Layers:

Texture: fine grained, sandpapery feel

Shiny: dull

Hardness:

Other: feels like sand paper

formed from sand

Shale

Sedimentary Rock

Color: black, brown, gray

Streak: black

Layers: yes

Texture: very fine particles, smooth, layered dirty feel

Shiny: light sheen

Hardness:

Other:

A common source of oil

formed from silt

Conglomerate or pudding stone

Sedimentary Rock

Color:

Streak:

Layers:

Texture: coarse grained rounded pebbles, bumpy Shiny: dull

Hardness:

Other: formed in a moving river as it deposits pebbles, sand, and mud together, then all were compressed.

Also known as pudding stone

Limestone

Sedimentary Rock

Color: always going to be grey (light or dark)

Streak: Layers:

Texture: fine particles powdery, often has fossils Shiny: dull

Hardness:

Other:made in coral reefs

forms from shells and calcite

Fizzes as it releases carbon dioxide when acid applied.

Parent rock of marble

Fluorite

Mineral

Color: purple, green to yellow or colorless

Streak: Layers:

Texture: smooth

Shiny: glassy or pearly

Hardness: Moh's scale 4

Other: makes massive crystals at times

glows in ultraviolet light

Used in the manufacturing process of steel

You can tell purple fluorite from amethyst quartz by the shape of the crystals.

Graphite

Mineral

Color: steel gray

Streak: Black

Layers:

Texture: greasy

Shiny: dull metallic

Hardness: Moh's scale 1

Other:

made of pure carbon

Uses: "lead" in pencils, sporting equipment like golf clubs, tennis racquets, and fishing poles

Gypsum - satin-spar

Mineral

Color: white, gray, pearly

Streak:

Layers:

Texture: fibers

Shiny: satiny metallic luster

Hardness: Moh's scale 2

Other: used to make insulation, plaster of paris and drywall

Hematite

Mineral

Color: steel gray, reddish brown

Streak: red brown

Layers:

Texture:

Shiny: metallic

Hardness: varies on Moh's scale 1-6.5

Other: important ore of iron, used to make steel

in its reddish form, the redness is caused by the rusting (oxidizing) of the iron inside

Kaolinite

(light area)

Mineral

Color: white, sometimes colored by impurities

Streak: Layers:

Texture: rough, clay like

Shiny: no

Hardness: Moh's scale 2

Other:

Quartz - chert

Mineral

Color: various, white to gray is common

Streak: colorless or light colored

Layers:

Texture: smooth, chalky, waxy

Shiny:

Hardness: Moh's scale 7

specific gravity: 2.65

Other: part of the quartz family

has been used in the past to make arrowheads

Talc (soapstone)

Mineral

Color: white, green, or pink

Streak:

Layers:

Texture: slick/soapy

Shiny: pearly/waxy

Hardness: Moh's scale 1

Specific gravity is 2.58

Other: Also known as soapstone

Bituminous Coal

Sedimentary Rock

Color: black or dark brown

Streak:

Layers: yes

Texture: sooty

Shiny: bright and dull bands

Hardness: softer than anthracite coal

Other: Contains very tiny fossils

lower carbon content than anthracite coal

Gneiss

Metamorphic Rock

Color:

Streak:

Layers:no

Texture: coarse grains of minerals

Shiny:

Hardness:

Other: sometimes has bands (stripes) of different colored minerals caused by the reorganization of minerals during metamorphosis

Marble

Metamorphic Rock

Color: Comes in many colors Streak:

Layers:

Texture: Shiny:

Hardness: Moh's scale 3

Other:

Forms from limestone

Contains minerals calcite and pyrite

often carved by artists, relatively soft

fizzes with dilute acid

Pumice

Extrusive Igneous Rock

Color: light gray

Streak: Layers:

Texture: full of small similar-sized air bubbles "frothy"

Shiny: light sheen, not glossy

Hardness:

Other: used in soaps and polishes because of it's abrasive qualities

floats in water,very light

formed from lava that cools quickly, trapping air bubbles inside

Quartzite

Metamorphic Rock (formed from sandstone)

Color:

Streak:

Layers:

Texture: fine-grained

Shiny: Hardness:

Other:

Schist - garnet

Intrusive metamorphic rock (formed from magma, NOT lava, cools slowly)

Color: dark red to brown

Streak: colorless or light colored

Layers:

Texture:

Shiny: glassy or dull

Hardness: Moh's scale 6.5

Other: Can form garnet crystals

Slate

Metamorphic Rock

Color: varies

Streak:

Layers: breaks in layers

Texture: fine grained, minerals not visible

Shiny:

Hardness:

Other:

low-grade metamorphic rock, made up of mica

Anthracite coal

Metamorphic Rock

Color: black

Streak:

Layers: breaks in layers

Texture: fine grained, minerals not visible

Shiny: high luster (shiny, semi-metallic))

Hardness: harder than bituminous coal

Other: higher carbon content than bituminous coal

Define "Rock"

A natural combination of minerals.

What is "fracture"?

Fracture describes the shape or pattern of breakage that a rock or mineral shows when struck.

Desert Rose

Desert Rose is a crystalline form of either gypsum or selenite.

Both of these minerals are soft and can be scratched with your fingernail.

Cleavage describes:

directions that a rock or mineral can be easily split. It is a tendency to split along a definite plane yielding a flat surface. Rocks or minerals perfect cleavage may split into layers, cubes or other crystals.

Luster is:

The way a mineral reflects light. Is it shiny, metallic or dull?

A geode is:

A volcanic rock with a hollow middle where crystals grow.

Calcite

Mineral

Color: white/clear

Streak:

Layers:

Texture:

Shiny:

Hardness:

Other:

reacts to acid

Define "mineral"

A mineral is an inorganic, naturally occurring crystalline solid. It is made up of basic elements and compounds, like gold or sodium.

Extrusive igneous rock

Formed by the cooling of lava, outside the surface of the earth. Cools quickly.

Intrusive igneous rock

Formed by the cooling of magma, inside the surface of the earth. Cools slowly.

Metamorphic rock

Rocks changed from sedimentary or igneous rock by intense heat and pressure from plate tectonics or other sources within the earth's crust.

Milky quartz

Mineral

Color: white

Streak: colorless or light colored

Layers: none

Texture: smooth

Shiny:

Hardness: Moh's scale 7, Harder than glass, but softer than diamond or topaz

Other: the milky color is caused by impurities like moisture when the crystals form.

Rank in order from least to greatest specific gravity:

A. Kaolinite

B. Copper

C. Lepidolite

D. Pyrite

A - Kaolinite

C - Lepidolite

D - Pyrite

B - Copper

Bornite

Mineral

Color: iridescent, shades of blue and purple and brown

Streak: grayish black

Layers: Fracture is conchoidial (shell-like)

Texture: smooth

Shiny: Luster is metallic

Hardness: Moh's scale 3 to 3.25, softer than a penny or glass

Other: An important form of copper ore

Sediments

Small particles of any type of rock (metamorphic, igneous, or sedimentary) broken off by erosion or weathering. Can be used to form new sedimentary rock.

Calcite - dogtooth crystal

Mineral

Color: white/clear

Other:

A form of calcite that grows in the shape of dog's teeth, often in limestone caves near pools of water.

reacts to acid

rhomohedral crystals

Define "specific gravity"

The density of a mineral. Minerals with a high specific gravity will feel heavier than one of a low specific gravity for the same size piece.

How many chemical elements make up almost all (98%) of the earth's crust?

8

List the following in order from softest to hardest:

A. Quartz chert

B. Bornite

C. Talc

D. Galena

C. Talc

D. Galena

B. Bornite

A. Quartz chert

How are sedimentary rocks formed?

Layers of sediment are cemented together over time.

What is the state stone of Texas?

Petrified Palmwood

Who created the hardness scale used to classify rocks and minerals?

Frederick Moh

Which kind or kinds of energy and force drive the rock cycle?

Solar, radioactive, and gravity

What is physical weathering?

The breakdown of rocks without chemical change. Usually this is caused by abrasion.

What is chemical weathering?

Chemical reaction can break the bonds that hold rocks together causing them to crumble. Water is often a key ingredient to this, as well as warm weather.

What is biological weathering?

This is caused when plants or their roots push or pull rocks apart.

What causes erosion?

Wind, water, ice, and gravity can cause the movement of materials like soil, sand, silt, or sediment.

When rock cools more slowly, how does it affect the size of crystals that form in the rock?

The more slowly it cools, the larger the crystals will be.

What kinds of rock might have fossils?

Most are found in sedimentary rock, but some are in metamorphic rock too.

How are magma and lava different?

Magma is molten rock INSIDE the earth's surface. Lava is what we call it once it is above the surface.

What happens to water when it freezes?

It expands. This can get into cracks in rock and force the rock apart.