rocks and minerals Flashcards
definition of minerals
a mineral is a naturally occuring solid elements or inorganic compound with characteristic chemical composition ,atomic structure and physical properties
facts about minerals
Almost all of Earth’s crust is made up of minerals
most minerals are of single elements - gold, silver diamonds
a constant chemical formula
definition of rock
a rock is a solid aggregate made up of one or more minerals - some rocks are generally made up of one mineral - limesone -calcite however most of them are made up of 2 minerals - granites and basalt
name the 3 types of rock
igneous - form through the solidification of molten rock -basalt and granites (basalt- extrusive rocks formed by the quick cooling of surface lava)(Granites- intrusive rocks- slow cooling of magma trapped in chambers)
Sedimentary rocks - formed from the deposition (fossil fuels ) and lithification ( hardening ) of sediment on Earth’s surface and within water bodies ( seas , lakes etc)
metamorphic rock- formed from other rocks as a result of heat and pressure -Both igneous and sedimentary can be changed into metamorphic rock
metamorphic rock
heat result from depth below surface and volcanic activity whilst pressure from earth movements . - they are hard and resistant to erosion- marble and slate .
the different kinds of metamorphism
regional - moderate to high temperature - continent collision zones and subduction zones
contact ;high temp/low temp - when an igneous body intrudes a pre-existing rock
hydrothermal; fluids circulating - mid-ocean ridges
define weathering
the gradual breakdown of earth’s rocks and minerals into smaller fragments by exposure to environmental conditions -
mechanical weathering
involves physical breakdown of rocks - temperature changes causes expansion and contraction causes rocks to crack - in the desert
chemical weathering
involves chemical reactions between rock material and environmental chemicals - oxygen ,co2,water
biological weathering
involves plants and animals - roots digs in and wedge rocks
define erosion
the process by which earth’s surface is worn away - caused by water and wind - involves the physical removal of material- they are eventually deposited and accumulate on earth’s surface
sediments of aquatic origin
contain large amounts of hard dead organisms - biogenic sedimentation - accumulated sediment is consolidated and compressed and can be lifted by Earth’s movement
stratification
occurs due to variation in deposition
summary of rock cycle
1) igneous rock by the solidification of magma
2) igneous and sedimentary rocks are changed into metamorphic rocks by the effects of temperature and pressure
3) igneous ,sedimentary and metamorphic rocks can be exposed to geological uplifting - once exposed all rocks can be converted - sedimentary rocks
4) deep within earth’s asthenosphere especially at subduction zones where rocks melt and become magma again
name the 5 different sedimentary rocks of the maltese island
1) upper Coraline limestone
2) greensand
3) blue clay
4) globigerina limestone
5) lower Coraline limestone
