Where pools of water containing the appropriate ions in concentration dry out.

Typically a very arid (dry) climate.

Water runoff from mountains collects in rapidly drying desert lakes.

eg. Death Valley; Great Salt Lake

high water areas along arid coastlines

eg. Persian Gulf, Saudi Arabia

found on continents that fill with marine water

eg. Michigan Basin; Gulf of Mexico

non-marine evaporite (Boron)

once used as a cleaning agent

eg. 20 Mule Team Borax

ionic bond - salt of our blood and tears

used in food production and preservation, water softening, to melt snow and ice

used to make plaster

eg. frescos

Sulfur

occurs as a native element near the fumeroles of volcanoes

more commonly mined by sending hot water into salt domes to melt the sulfur

used in war - suffocating gases;  gunpowder

today most used to manufacture drugs, fertilizers, explosives, and pesticides

comes from the evaporite mineral borax mined in Death Valley

used in glass products (Pyrex), laundry and cleaning products, food preservatives, ceramic glazes

the numbers (eg. 5-10-10) on fertilizer bags refer to % of nitrogen (N), phosphorous (P), and potassium (K)

(N) - green leaf growth

(P) - roots + flowers

(K) - fruit

Saltpeter or Niter

natural nitrate evaporite deposits that are extremely rare - very soluble

occur in very dry regions (eg. Atacoma desert in Chile) or caves produced from manure and urine

Nitrogen

mostly obtained synthetically from atmospheric nitrogen and natural gas by the Haber Process - produces ammonia

most important chemical process of 20th century - prolonged WWI and led to the population explosion as fertilizers increased food production

found in guano deposits from birds and in bone

pilgrims learned from Indians to bury fish and bones with corn - bone meal

problem: insoluble

when dissolved in sulfuric acid, becomes soluble (superphosphate)

comes from evaporite materials such as sylvite

huge deposits in Canada, New Mexico, Texas, Oklahoma, and Kansas

• malleable
• ductile
• alloys
• conduct heat and electricity

Malleable

Ductile

combines with other elements to take on significant new properties

tend to have superior properties to the original metal

accounts for more than 95% by weight of all metals consumed because:

• abundance - 3rd most abundant metallic element after silicon and aluminum
• ease of smelting - separating metal from its ore
• easily alloyed - results in tempered, sharpened, and welded objects that are exceptionally strong and durable

an alloy of iron and other elements

•  corrosion resistance - add nickel
• high temp. hardness - add chromium, cobalt, tungsten, molybdenum

1. magnetite crystallizes in pluton's magma and settles to bottom of the deep magma chamber forming thick layers
2. hydrothermal deposits - hot water-rich fluids escape from magma chamber or come from groundwater into fractures surrounding rock crystallizing iron minerals

1. Bog Iron Deposits - (Revolutionary War) smallest deposits; occur in formerly glaciated and coastal regions where bogs with decaying vegatations interact with iron-rich clays
2. Ironstones - (Civil War) many sandstones and shale contain hematite cements that originally from the leaching of huge quantities of iron from old soil
3. Banded Iron Formations - most abundant source of iron (nonrenewable); consists of alternating bands of hematite and red chert; Lake Superior area

most is done by open pit (surface) mining; removed in a series of steps called benches

most iron ore must be further concentrated (beneficiation) - removing impurities and packed into small pellets to be shipped to the smelters

began more than 4000 years ago in Anatolia, Egypt, and Mesopotamia

Iron Age replaced Bronze Age around 1200 BC

ingredients:

• coke (C) - heating coal in absence of air
• limestone - used to absorb/separate undesirable elements; creates slag
• iron ore

second most abundant metallic element in earth's crust

very hard to free from the minerals in which it occurs

lightweight and resistant to weathering

less effective in conducting electricity

found at pyramid on top of Washington monument (once worth more than gold) 

• used in packaging and containers (35%)
• transportation - over 150lb in avg. car (20%)
• building (18%)
• electrical wire (9%)

Where is Aluminum found?

in many silicate minerals (feldspar micas); rarely found concentrated enough to make an ore

Bauxite - ore of aluminum; forms as part of a soil in tropical climates

requires abundant, cheap electricuty (usually shipped to Norway, Canada, US)

mixed with cryolite and electrodes; electricity is passed through, and molten aluminum forms around electrodes

occurs as a native element

Copper Age brought humans out of Stone Age around 6000 years ago

• during WWII, copper so important pennies were made of steel 
• electrical wires
• pipes for plumbing
• alloys bronze (copper + tin) and brass (copper + zinc)

porphyry copper formed from igneous hydrothermal solutions

largest man-made excavation in the world - 2.5 miles wide and .5 miles deep

15 million tons of copper have been removed

 soft and resists corrosion and rusting - used for galvanizing steel

used to make brass

used as zinc oxide in paint pigments, ointments, and lotions to prevent sunburns

very dense, soft, and has a low melting temperature

used in automobile batteries, additive in gasoline, in paint pigments, ammunition, in electrical and plumbing solder, and for x-ray and radioactive shielding

more malleable than gold

easy and cheap to smelt 

• sphalerite
• galena
• smithsonite (named after founder of Smithsonian Museum)

metallic gold is soft, malleable, dense and corrosion-free (noble metal) 

• doesn't tarnish
• doesn't mix with other minerals
• very valuable - not a lot of it; most gold ever mined still in use today

gold deposits first form as hydrothermal solutions, typically in altered country rock (rock that was there before magma) around granite magmas 

• 1st - converging plate boundaries
• 2nd - rivers, streams (placer deposits)

are water-rich fluids containing lots of left-over quartz, feldspars, even micas from the granitic magma along with much heavier elements (gold, silver, copper, etc)

often form veins in the country rock with very large crystals called pegmatites

where most gold is found 

• the mother lode erodes and the gold survives, transported by water
• gold settles-out on stream bottoms (in unconsolidated sands and gravels) which can be shoveled or dredged in pans or into long sluiceways.