Minerals, Rocks and Fossils
What is a mineral?
• Naturally occurring • Non-organic • Characteristic chemical composition • Distinctive physical properties • Crystalline structure
Mineral properties
• Color • Luster • Habit (Shape) • Cleavage & Fracture • Streak • Hardness • Other
Color:
Not mineral specific
Luster:
How minerals reflect light
Metallic
Nonmetallic
Mineral Habit (Shape)
Shape a mineral takes if grown unimpeded
Mineral Java Applet
Cleavage & Fracture
Cleavage: planes of weakness along which minerals can break
Fracture: surfaces along which minerals can break
Cleavage & Fracture
Best identified on a fracture surface
Streak:
The powdered form of a mineral
Hardness:
Based on Moh’s scale of hardness
Other Properties
• Specific gravity • Reaction to acid • Striations • Magnetism
Classifying Rocks
• Rocks are classified by how they formed and
• • • •
what they’re made of There are 3 general classes of rocks Igneous Rocks…are formed when lava and magma crystallize to form solid rock Metamorphic Rocks…are formed when an existing rock is partially melted, squeezed, or both Sedimentary Rocks…are formed when sediments (sand clay, and silt) are compressed and become solid rock
Igneous Rocks
Metamorphic Rocks
Gneiss
Schist
Sedimentary Rocks
Shale Conglomerate
Sandstone
Fossils
The remains or imprints of living things of the past found in Sedimentary rocks.
Fossils provide information about life and conditions in the past.
Fossils of Sea Creatures
• Oceans once
covered the area • What part of the ocean
Fossils of Plants
• Plant fossils can
tell us about the ancient environment
Animal Fossils
• Animal fossils can
tell us
– About past environments – What the animal ate – How they lived