Minerals & Rocks
 Minerals
 naturally occurring, nonliving or inorganic
substance that can be written as a chemical
formula.
 Quarts = SiO2
 have a definite internal structure and a
characteristic set of physical properties
 about 3500 known minerals in the Earth’s crust
(about 20 minerals make up 95% of all rocks)
 ex: mica, quartz, calcite, etc.
 Rocks
 composed of a variety (mixture) of minerals in
different combinations & amounts
 results in rocks having unique properties
(pourous, granular, smooth, soft or hard,
different densities, and vary on color)
 3 main types of rocks
o Igneous Rocks
 rocks formed when magma (molten rock) cools
& solidifies
 characterized by crystals of various minerials in
its structure
 the slower it cools, the larger & more abundant
the crystals
 extrusive igneous rocks – cools on the Earth’s
surface (faster) – Crystals are very small and
usually cannot be seen with the unaided eye. basalt, obsidian
 intrusive igneous rocks – cools beneath the
Earth’s surface (slower) – Crystals will be much
larger and can be seen with the naked eye. Their
color is lighter. These rocks tend to take many
years to form – granite
o Sedimentary Rocks
 Sometime though of as recycled rock
 rocks formed from fragments of older rocks,
sediments, and sometimes fossils compressed or
cemented into layers
 Sediment is small pieces of rocks produced from
physical & chemical weathering which settles
into and accumulates in an areas coupled with
precipitation & weight forming rock.
 Minerals dissolved in water seep into bits of
sediment and glue the bits together.
 Sedimentary rocks are named by the size of the
sediment that fuse together: pebbles fused =
conglomerates, sand fused = sandstone, mud and
silt fused = shale, or fossils of organism that
remain in the water for long periods of time
coupled with pressure = limestone.
o Metamorphic (changed) Rocks
 Rocks formed when other rocks are exposed to
intense heat, or pressure with out melting over a
long time causing a chemical change.
 Marble is a limestone (sedimentary rock) put
under extreme heat and pressure for a very long
time.
 Slate is mudstone or shale formed due to heat and
extreme pressure.
 Metamorphic rock is very hard and can usually
be split along planes and can create large flat
surfaces.
Properties of Rocks
o Igneous Rocks
Crystals (large & small)
Random dispersion of crystals & minerals
Holes/porous
Small crystal – darker in color
Large crystals – lighter in color
Ruff Texture
Looks like glass
o Sedimentary Rocks
Fossils Present
Gritty texture (may come off by handling)
Possible layering of same materials
Clumps of materials cemented together
Named due to size of Sediments
Compressed/glued together
Most Common
o Metamorphic Rocks
Smooth flat surfaces
Shine or sheen to it
Layers of banded materials
Swirly layers, decorative look
Hard or dense surface
Rounded or curved edges
Non-Pourous
The Rock Cycle
 “old rocks make new rocks”
Erosion &
Deposition
Melting
Temperature
& Pressure
Erosion &
Deposition
Temperature
& Pressure
Melting
The Rock Age
 The ages of rocks are determined using
several methods
 Superposition may determine relative age:
o Assuming no disturbance in the position of the
rock layers, the oldest will be on the bottom and
the youngest will be on the top.
 Using fossil remains to determine the age
 Radioactive dating may determine absolute age:
o Comparing the amount of undecayed radioactive
elements to the decayed amounts of these
elements is used to determine age.
Minerals & Rocks
 Minerals

naturally

Quarts
 have a definite
 about 3500
 ex:
 Rocks
 composed
 results
 3 main types of rocks
o Igneous Rocks
 rocks
 characterized
o
 the slower
 extrusive igneous rocks
 intrusive igneous rocks
o Sedimentary Rocks
 Sometime
 rocks
o
 Sediment
 Minerals
 Sedimentary rocks
o Metamorphic (changed) Rocks
 Rocks
 Marble
 Slate
 Metamorphic rock
Properties of Rocks
o Igneous Rocks
o Sedimentary Rocks
o Metamorphic Rocks
 “old rocks
Erosion &
Deposition
The Rock Cycle
Melting
Temperature
& Pressure
Erosion &
Deposition
Temperature
& Pressure
Melting
 The ages
The Rock Age
o Superposition
 Assuming
 Using fossil
o Radioactive
o
Comparing the amount