Silicates – are the most abundant family of minerals on Earth
 They contain the most abundant elements on Earth – silicon
and oxygen (page 11 ESRT)
 Quartz – most common mineral on Earth, you can go
anywhere and find quartz
*There are 12 common minerals that can be found almost anywhere on
Earth.*
like: Quartz, mica, feldspar, olivine,
hornblende, etc.
Silica Tetrahedron – is the basic building
block of all silicates
 1 silica atom
 4 oxygens
 shaped like a pyramid
Differ by internal arrangment of atoms.
(how they are put together)
Rocks: 3 types
I. Sedimentary:
A. Clastic: composed of fragments or pieces of rock (sediments)
1. Compression: great force or weight from above
(dewatering- water gets squeezed out)
ex) shale, siltstone, sandstone
2. Cementation: mineral cement from groundwater
ex) conglomerate, breccia, shale, siltstone, sandstone
common cements: CaCO3= calcium carbonate (dissolves in acid), FeO2
= iron oxide = rust, Silica
B. Non-clastic: chemical
1. Precipitation: mineral comes out of solution, settles to
the bottom = called precipitates
ex)gypsum, limestone, halite, dolostone
2. Evaporation: mineral is deposited after water evaporates
C. Organic / Biologic
1. can be clastic, can form from compression of once living
things
Ex) coal, peat, fossil limestone (cocina)
II. Igneous Rocks: formed by melting, cooling and solidifying
A. Intrusive: forms inside the Earth, MAGMA, has large crystals
because they cooled slowly a.k.a. plutonic : granite and gabbro
B. Extrusive: forms outside the Earth (on the surface), LAVA,
has small or no crystals because it cools fast a.k.a. volcanic : pumice, obsidian,
rhyolite, basalt
Granite = continental crust
Basalt = oceanic crust (contains no salt)
Crust is mostly igneous with a thin covering of sedimentary rocks.
***As cooling rate increases, crystal size and shape will decrease.****
III. Metamorphic Rocks: form from heat and/ or pressure
A. key characteristics
 Recrystallization
 Foliation
 Distortion
 Banding
B. regional: large area
Ex) Adirondacks
C. contact: small area
Ex) where igneous rocks touch other rocks