Intro to rocks Flashcards
1.10-1.14
rock defintion
a coherent naturally occurring solid that’s consists of an aggregate of minerals or less commonly a body of glass
define coherent
holds together on its own and must be broken in order to separate into smaller pieces
do unnatached mineral grains consitute a rock
no
Two main types of rocks
crystalline and clastic
crystalline rock are
rocks whose grains interlock with one another like a puzzle
granite (clast or cryst)
crystalline
crystalline rocks grew
when an igneous melt solidified
clastic rocks are
rocks that consist of separate grains that have been cemented together
natural cement is composed of
minerals that have precipitated from water
sandstone (clast or cryst)
clastic
Grain vs crystal are _ when talking about rocks
interchangable
grain defintion
mineral crystal in a rock or a fragment that has broken of either another rock or larger piece of mineral and has since almagamated forming another rock
we will use the term crystal only when
referring to a piece of a single mineral that displays faces
glass rock example
obsidian
glass rock
either originated as a continuos mass or formed through the welding together of individual glass grains when they where still hot
Three rock study scales
Hand sample
outcrop
thin section
Hand sample
medium scale
what we do in labs
outcrop
large scale
identifies basic rock types
thin section
petrographic microscope
used to identify compostion
High tech equipment is
more accurate but expensive
2 forms of surface rocks
fragmented chunks
bedrock
broken chunks or fragments are
pebbles cobbles or boulders
“clasts”
broken off bedrock by wind water ice or gravity
can be transported from source
bedrock is
attached to the earths crust
surface exposure is outcrop
good for building on
3 PRIMARY TYPES OF ROCKS
igneous
sedimentary
metamorphic
igneous rocks form from
molten material