What are ores?
Ore is natural rock or sediment that contains one or more valuable minerals, typically containing metals, that can be mined, treated and sold at a profit.
The societal importance of ores
Mark Hoggard writes
Copper, lead, and zinc form three of the four base metals (the other being nickel) and are heavily relied upon by modern society. Copper’s high electrical conductivity means that it is utilised in virtually all electronics and wiring. Lead is used in photovoltaic cells, high-voltage power cables, batteries, and super capacitors. Zinc is used in batteries and paints, but also in agricultural fertilisers and fungicides since it is a limiting micronutrient in many of the world’s crop soils.
from Treasure maps, sustainable development, and the billion-year stability of cratonic lithosphere
Many minerals are used in our smartphones, tablets, computers, and all home electronics:
Some thoughts to ponder!
How many pounds of minerals are required by the average person in a year?
How large is a lifetime supply of minerals for the average person?
How do we find ores? Prospecting
Classically, people would walk around and dig into the ground. They’d examine the soil and rocks to see if there were any significant amounts of important minerals, metals, gems, etc. This was called prospecting. Even 2000 years ago people in many civilizations had simple ways of doing this.
By the time of the industrial revolution (1780s to 1830s) most easy surface deposits had been used up. From here onwards, corporations needed to employ many scientifically literate explorers to systematically dig and drill into many places all across the globe.
Chemists and geologists would carefully examine samples, determining if there was enough ore to make it economically worthwhile to mine that area.
To some extent this also happens today. Here we see geologists from the USGS and the New Mexico Bureau of Geology and Mineral Resources examining a carbonatite dike in the Lemitar Mountains, New Mexico.
Geologists examining a carbonatite dike, USGS
However, that kind of prospecting is less common today. We have to come to rely on various high tech strategies that let us find ore deposits that otherwise are more difficult to find.
There are now ways of Finding ores in underwater ocean deposits
Marine self-potential survey for exploring seafloor hydrothermal ore deposits, Yoshifumi Kawada & Takafumi Kasaya
We have remote sensing from airplanes flying overhead. Airplanes carry sensors which look at the ground with in visible and infrared light imaging spectrometers.
For instance, APEX is an airborne imaging spectrometer developed by a Swiss-Belgian consortium on behalf of ESA
APEX consortium, apex-esa.org
In our generation we use explore Earth for minerals deposits using remote multispectral imaging; these sensors are on satellites in Earth orbit.
Read about Mineral Exploration of Earth from Satellites in Space.
One such example is Terra (EOS AM-1.) This is a multi-national, NASA scientific research satellite. And below we see the Copernicus Sentinel-2 satellite from the ESA (European Space Agency.)
Image from Astrium GmbH. https://www.esa.int/Applications/Observing_the_Earth/Spotlight_on_Sentinel-2
Mining: How do we remove mineral from the Earth?
Prospecting is all about finding the right places to find ores. The next challenge is mining, getting these materials out of the Earth, grinding them up, and then transporting them off to factories.
In some locations there are great, open wounds on the fact of the Earth, where we see giant machines slowly digging into the Earth, in ever-wider and ever-deeper areas. Over a period of years tremendous amounts of materials ate pulled out of the Earth.
The advantage is that we obtain the minerals we need or want for our society.
The disadvantages are that badly damages the local environment and ecology. This often has deleterious side effects for people who locally. This is why we need people educated in geology, the scientific method, philosophy and ethics to be a part of this process.
Refining the ores
Next is refining (separating the metal from the other materials that it is mixed in)
Here are metals once they are refined, but before they are made into useful products.
Finally one will form the metal into an industrial product.
There’s quite a separate process, of course, for removing gemstones from the ores that they are found in.
Gem-containing ore are valuable and highly sought after:
The five cardinal gems of antiquity. Clockwise from top: Sapphire, Ruby, Emerald, Amethyst, Diamond. (Cardinal gems, Wikimedia Commons)
Examples of ores
Oxide mineral ores
https://openpress.usask.ca/physicalgeology/chapter/5-3-mineral-groups-2/
and
.
How are ore deposits created?
Weathering creates many important mineral deposits by concentrating minor amounts of metals that are scattered through unweathered rock into economically valuable concentrations.
Called secondary enrichment:
(A) In one situation, chemical weathering coupled with downward-percolating water removes undesired materials from decomposing rock, leaving the desired elements enriched in the upper zones of the soil.
(B) The second way is basically the reverse of the first. That is, the desirable elements that are found in low concentrations near the surface are removed and carried to lower zones, where they are redeposited and become more concentrated.
Ores from hot water, American Museum of Natural History
Some ore deposits are formed through hydrothermal/plutonic intrusions.
Some Caribbean have such deposits – Jamaica and bauxite
Some ore deposits in western states (copper, iron) may have been originally formed in deep sea hydrothermal vents that were scraped or accreted from the edges of various terranes that make up those states.
External reading
Evolutionary and Revolutionary Technologies for Mining, Technologies in Exploration, Mining, and Processing
Learning Standards
TBA
KaiserScience 