Minerals and Rocks

MINERALS AND ROCKS

1st gradeMINERALS AND ROCKSThe Earths crust is made up of ROCKS.The rock is made up of minerals.

MINERAL:A MINERAL IS A SOLID SUBSTANCE WHICH ORIGINATES THROUGH ONE OF THE EARTHS NATURAL PROCESSES. The general definition encompasses the following criteria:Natural occurringStable at room temperatureRepresented by a chemical formulaUsually abiogenicOrdered atomic arrengementMOST COMMON ELEMENTS IN MINERALS:OxygenSiliconAluminiumIronCalciumSodiumPotassiumMagnesium

CRYSTALWhen the external shape of the mineral reflects its internal structure, we call it a crystal.(Crystal of Amethyst Quartz) (Cuarzo amatista)

PHYSICAL PROPERTIES OF MINERALSCOLOUR: some minerals are always the same colour (cinnabar), others shaw variety of colour. (Quartz)LUSTER (brillo):it is how minerals look when it reflects light: metallic, vitreous, pearly, dull or greasy.

PROPIERTIESHARDNESS (dureza): it measures the comparative ease or difficulty with which a mineral may be scratched.Fingernail: low hardnessNail: mediumIt scatches glass: high

Mohs scale

PHYSICAL PROPERTIESSTREAK (RAYA): it is the colour of the mineral when it is made into powder.FRACTURE AND CLEAVAGE (Fractura): it is the tendency of a mineral to break along irregular surfaces (fracture) or along flat planar surfaces (cleavage).Concoidal fracture and cleavage

ROCKSAggregates of minerals which have been formed in a natural process.According to that process rocks can be sedimentary, metamorphic or igneus.

THE ROCK CYCLE

SEDIMENTARY ROCKSThese are formed from materials called sediments, which are slowly deposited in some areas (oceans and lakes).Sediments accumulate forming horizontal layeers called strata.Examples: limestone: piedra caliza sandstone: areniscaSEDIMENTARY ROCKS

METAMORPHIC ROCKSThese are formed from other rocks that are transformed by the high pressure and temperature in deep zones of the Earths crust. The process is called metamorphism.

Clay changes into slate. (arcilla se transforma en pizarra)Limestone changes into marble .(caliza se transforma en mrmol)Marble - mrmol

Slate - pizarra

Gneiss - gneis

Moscovite schist esquito micceo

MAGMATIC OR IGNEOUS ROCKSIn deep zones of the Earths crust there are extremly high temperatures which can melt rocks, which become molten materials called magama. When this magma cools down and solidifies, it forms igneus rocks.

Plutonic rocks: magma cools down very slowly under the Earth. Granite (granito)Volcanic rocks: magna cools down quickly as it comes out of the volcano. Basalt and pumice (basalto y pumita)Magmatic rocks: granite and pumice