Read pages 192 – 200 in blue book, and Section F, pages 118-138 in packet from Prentice-Hall (brown) book When finished with reading, begin working on the minerals vocabulary

Geology!

What is Geology? Geology is the study of the Earth, the materials of which it is made, the structure of those materials, and the processes acting upon them. It includes the study of organisms that have inhabited our planet. An important part of geology is the study of how Earth’s materials, structures, processes and organisms have changed over time.

Minerals … Why study ‘em? Building blocks of planet Industrial minerals Ore minerals Energy resources Gems Environmental hazards

So, then what is a rock? What is a mineral? Hematite Homogeneous Naturally occurring Inorganic Solid Definable chemical composition Orderly arrangement of atoms in a lattice Quartz So, then what is a rock? A rock is an aggregate of one or more minerals. Granite, an igneous rock Sandstone, a sedimentary rock Gneiss, a metamorphic rock

What is a crystal? A piece of homogeneous solid substance having a natural geometrically regular form with symmetrically arranged plane faces. Halite Quartz

Crystals have an orderly arrangement of atoms or ions The shape of the crystal reflects the internal atomic structure. Halite crystals Atomic structure of Halite

Properties used to identify minerals Luster Color Streak Hardness Crystal Form Cleavage Special Properties Specific Gravity

Luster Describes how a mineral reflects light Metallic minerals have the luster of polished metal

Luster Describes how a mineral reflects light Nonmetallic “Vitreous” (glass-like) “Dull” or “Earthy” “Pearly”

Luster Describes how a mineral reflects light Nonmetallic “Greasy” “Silky” “Waxy”

Color Often not reliable! Except for some… May result from impurities Olivine = olive green Sulfur = yellow

S t r e a k Color of the mineral when in powdered form Streak color Varieties of Hematite streak reddish-brown White Streak Plate

of a minerals resistance Moh’s Hardness Scale Soft Hardness is a measure of a minerals resistance to being scratched. It is determined using the “scratch test.” Moh’s Scale is based on a relative scale based on minerals and common materials. 1) Talc 2) Gypsum -- fingernail at 2.5 3) Calcite -- copper (old penny) at 3.5 4) Fluorite 5) Apatite -- nail 6) Feldspar -- streak plate or good steel file at over 6.5 7) Quartz 8) Topaz 9) Corundum 10) Diamond Hard

Tendency of a mineral to break on flat planes of weakness. Cleavage Tendency of a mineral to break on flat planes of weakness.

Cleavage vs. Crystal face Cleavage planes repeat No repetition of crystal face within crystal Crystal Faces Crystal Faces Cleavage Planes

Cleavage example in Calcite Planes of cleavage are parallel to each other Notice the double refraction Cleavage example in Calcite Cleavage planes look like box that has been pushed over 18

Notice how this sample shows many crystals grown together Cleavage in Halite (salt) Cleavage planes Cubic cleavage Two directions at 90 Notice how this sample shows many crystals grown together

Minerals Lab Activity

Feldspar – Sample A

Quartz – Sample B

Calcite Sample D

Fluorite Sample E

Hematite Sample G

Gypsum Sample H

Magnetite Sample I

Muscovite Mica Sample J

Talc Sample L