Rocks and minerals images

Rocks and minerals

 

What are rocks and minerals?
How are they formed?
What are the different types of rocks and minerals?

 

 

 

A rock is any naturally occurring and coherent solid mass or aggregate of minerals or mineraloid matter.

 

Naturally occuing means that they may be made by animals (pearls or ivory), but not by humans.  

 

Coherent means that it is united and consistent.

 

Aggregate of minerals or mineraloid matter means that rocks are made up of smaller substances called minerals.

 

Rocks are usually categorized by the minerals in them, their chemical composition, or the way in which they are formed.

 

Rocks are usually grouped into three main groups: igneous rocks, metamorphic rocks and sedimentary rocks based on how they are made.

 

Minerals are naturally occurring, homogeneous, inorganic solids having a characteristic chemical composition and crystalline structure.

There are lots of minerals.  We will look at some of the more important ones in this unit.

 

Homogeneous means that the minerals are uniform and all alike within.

 

Inorganic means that they are not produced by living things (ivory, pearls, petrified trees, amber, etc.)

 

A characteristic chemical composition and crystalline structure means that the chemicals inside them bind in predictable and dependable ways forming a crystal structure.  

 

 

Let's look more closely at some of the more common rocks and minerals.  

We'll begin with rocks based on how they are formed:

 

Igneous - created by cooling of molten rock

Sedimentary - created by cementation of small sediments of rock

Metamorphic - created by partial melting and squishing due to intense heat and pressure

 

As you can see from this, the same materials on Earth's surface keep getting recycled and change forms.  The Earth is dynamic (ever changing).  

 

Let's begin with the first rocks...igneous:

There are two types of magma, so there are two types of igneous rocks...Mafic (dark and heavy) and Felsic (light).

Also, these rocks could be cooled slowly underground and get big crystals or erupt and form so quickly that they have tiny crystals:

Know Granite, Pumice, Gabbro, Basalt, Scoria, and Obsidion

 

 

Now let's look at sedimentary rocks:

These rocks are cemented from sediments of other rocks.  They are defined by what sediment makes up the rock.  Sand sediment makes sandstone...salt makes halite...clay makes shale...etc.

These rocks are made gently and preserve footprints and fossils best.

Know shale, sandstone, conglomerate, limestone, halite.  Coal and gypsum are also to be known, but coal is usually considered metamorphic and gypsum a pure mineral.

 

 

Now let's look at metamorphic rocks:

These are created by adding significant heat and pressure to other rocks.  They are characterized by what rock they started as as well as how much of their minerals melted and reformed.

Know slate, schist, gneiss, marble, and coal.

 

 

 

 

Let's look closer at some of the minerals making up those rocks:

These minerals may be sorted and organized in myriad ways (hardness, cleavage, shape, color, properties, etc.)

 

 

Know sulfur, biotite, muscovite, magnetite, agate, turquoise, azurite, malachite, hematite, talc, gypsum, calcite, flourite, feldspar, quartz, amethyst, rose quartz, smoky quartz, olivine, galena, topaz, garnet, corundum, iron pyrite, graphite, diamond, jade, copper.

 

Are you ready for the test?

Define rock, mineral, and ore.
How would you tell is an igneous rock were mafic, felsic, intrusive, or extrusive?
    What does the texture tell us about the rock's formation?
Which type of rock would you most likely find fossils in?
    Why?
What causes metamorphism?
    Describe the effects of metamorphism.
Draw the rock cycle.

Identify rocks!

Granite, Salt and pepper appearance, light in color, large grain size

Pumice, Light in color, full of holes, floats in water, tiny grain size

Gabbro, Dark in color, large grain size

Basalt, Dark in color, tiny grain size

Scoria, Dark in color, full of holes, tiny grain size

Obsidian, Black, glassy, conchoidal fracture (sharp, circular breaks), tiny grains

shale, Layers of clay

sandstone, Sand cemented together, sometimes layered, bite sand

conglomerate, Mix of grain sizes cemented together

limestone, Light in color, bubbles with acid

halite, Clear, rectangles, salty

slate, Hard, shiny layers of clay (some metamorphism)

schist, Shiny rock (metamorphism pulled out the mica)

gneiss, Mangled layers / bands

marble, Hard, shiny, light in color, bubbles in acid

coal, Black, lightweight, streaks black, burns easily

sulfur, Yellow, burns blue

biotite, Thin, flat, dark layers 

muscovite, Thin, flat, light layers

magnetite, usually heavy and dark, always magnetic

agate, Tiger eye moving light patch

turquoise, Light blue

azurite, Blue rock

malachite, Green rock

hematite, May be polished silver or natural red, always streaks red

talc, Soft enough to rub off the powdered rock with finger

gypsum, White and soft (fingernail will scratch it)

calcite, Clear, squished square, doubles images

fluorite, Translucent and green

Apatite,

feldspar, Pink and edgy

quartz, Clear and translucent, hard

amethyst, Purple quartz

rose quartz, Pink quartz

smoky quartz, Grey quartz

olivine, Olive green rock

galena, Silver and cubical, smells like sulfur with acid

topaz, Translucent brown, very hard

garnet, Dark red, edgy

corundum, Extremely hard, ruby and sapphire

iron pyrite, Gold in color, squared, hard

graphite, Grey and streaks grey very easily

diamond, Clear, refractory, hardest

jade,  Milky green

copper, Green or brown, metallic

Flint, Easily broken