Rocks and Minerals


Mineral properties:
a) naturally occurring
b) homogeneous (same) inorganic (non-living) solid substance
c) definite chemical composition
d) crystalline structure
e) color
f)  hardness

Mohs Scale of Hardness: We use different tools to determine a mineral's hardness: fingernail, penny, nail, and a few key minerals.  Check the scale.

9corundum (ruby, sapphire)
8beryl (emerald, aquamarine)
6.5-7.5steel file
7.0quartz (amethyst, citrine, agate)
6feldspar (spectrolite)
5.5-6.5most glass
3calcite, a penny

Color - Color can be used to identify minerals, but don't use only the color to identify the mineral.  Alot of minerals might have the same color amongst them.

Be observant but cautious

Streak test- Streak a metal across a tile to observe the true color the mineral leaves behind.  More reliable than color of the mineral.

Cleavage and fracture- 
Cleavage is the way a mineral breaks.  Many minerals break along flat planes, or cleavages - some in only one direction, others in two directions, and some in three directions, or more.  Ex: Mica, Feldspar, Calcite, and Fluorite.  Tricky one is graphite, you need a hand lens to see the cleavages of this minerals.
Fracture is breakage that is not flat, mostly a jagged edges. Best example is quartz.

Luster- Luster is basically the way a mineral reflects light.  The three major types of luster are metallic, glassy, and earthy (dull).  I like to just describe luster as metallic or non-metallic.

Look closely

Other properties-
a) Magnetism is a distinctive property in a few minerals.  Best example: Magnetite
b) Taste is a distinctive tastes.  Best example: Halite and other evaporite.
c) Fizz is made when an effervescent reaction of certain carbonate minerals to the HCl test.  Example: Limestone
d) Heft is how heavy a mineral feels.  Density comes to mind.  Remember density is the relation of mass and volume of an object.



Igneous rocks are formed from molten rock materials.
Two types:
a) Intrusive - formed below Earth's surface.  Crystals grow large, cools slowly.

Diorite                                            Gabbro                                       Granite                                       Pegmatite

b) Extrusive - formed on or above Earth's surface.  Crystals are small, cools rapidly.

Andesite                                        Basalt                                         Obsidian                                     Pumice

Rhyolite                                          Scoria

Sedimentary rocks are formed from pieces of broken rock, shells, mineral grains, and other materials.
Three types:
a) Clastic (detrital)- formed from mechanical weathered debris (grains from other rocks)

Breccia                                         Conglomerate                              Sandstone                                   Shale


b) Chemical - formed when dissolved materials precipitate from solution.

Iron Ore                                         Limestone (some)                        Rock Salt
iron ore - hematitelimestonerock salt

c) Organic - formed from the accumulation of plants or animal debris.

Coal                                              Limestone (coquina) -shells         Limestone (chalk)

Metamorphic rocks are rocks that have been changed by heat, pressure, and chemical process usually while they are buried below Earth's surface.
These rocks have been changed in their texture and chemical composition.
Two types:
a) Foliated - layered or banded appearance caused by extreme heat and pressure. (increase heat and pressure can change the rock into another rock)
Parent rock of the following is a shale.(Parent rock: shale changes to slate, phyllite, schist, and gneiss)
With enough heat and pressure can change a granite to a gneiss.

Slate                                                                       can turn into a Phyllite                                     

can turn into a Schist                                            can turn into a Gneiss (banded)
muscovite schistgneiss

b) Non-foliated - do not have a layered appearance.

Parent: Limestone into Marble                                 Parent: Sandstone into Quartizite

Video of the rock types:

YouTube Video

Rock Cycle - A great way to show the journey of three rock types.

Photo: Friday funny!  Name the three types of rock.  Click Like if you started with IGNEOUS, not CLASSIC!

Bonus:  Look at the bottom of this page for subpages (1) and click on the 

link to find out more.
Needs to be turned in by beginning of class: October 18th