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With over 2500 different minerals and over 100 with major economic uses some classification is needed. As metals have become more and more important in society we have added new groups of minerals to the heading economic - and we have dropped some rocks and minerals off the list as well if we follow the history of technology we can see some of the development of these groups. The first four groups are the tool stones, construction materials , Gemstones, and the precious (coinage) metals - all are know from before written history in he case of cutting tools to as much as 2 million years ago.

Tool stones are such materials as flint and obsidian that can be worked to make useful (cutting) tools.

Construction materials included not only such rocks as slate, sandstone, limestone and marble but also such materials as clay and mud that could be used to make structures or containers.

Gemstones are any colorful or patterned earth materials used for jewelry, sculpture, or decrative artifacts. They also include some use as decrative building materials.

Precious metals (gold, silver, copper) were used for decoration and religious artifacts, all were available to some extent as free materials.

With the development of fired pottery some things began to change - or so its believed :> the temperatures needed to fire clay into pottery are also hot enough to melt certain sand, lime, and salt mixtures giving rise to the first glasses and they are hot enough to burn off the sulfur from copper, lead, silver, and zinc minerals. As these are often found together some alloying resulted - especially with the copper and zinc and with copper and arsenic. So brass and bronze were developed with this the value of copper relative to gold and silver dropped as it was much easier to obtain in quantity and so it became the primary metal of the Base metals - base was used to separate them on a value level from the precious metals :>

The base metals are those that are either found with copper or alloyed with copper and now include all the copper, lead, zinc, arsenic and tin ores. Tin works as a much better metal to alloy with copper than arsenic in making bronze - but its much rarer. Zinc actually wasn't known to the ancients as it either was completely oxidized and went right up the furnace chimneys or reacted with copper to make brass directly in the furnace.

Everyone with me so far?

EW: we didn't know arsenic as a mineral

yep Arsenic is an element

EW: isn't arsenic a poison?

yes it is son, its an element that is poisonous - and something of a hallucinogen also

EW: oh ok for some reason we thought it came from a plant

P: Hell, so did I actually :>

EW: rat poison ;>

It was the poison used in Italy during the Renaissance by the Borgias - because its symptoms are those of extreme heartburn and food poisoning and because you can builds up an immunity to it by eating less than lethal doses.

P: Got some of that about ten feet away from me, I think I'll leave it where it is though :>

EW: wasn't there a movie arsenic and old lace or something like that

almonds have a different poison - cyanide (in trace nonlethal quantities) that gives them their flavor <G>

Pangea: Doesn't potassium nitrate have it too?

No potassium nitrate only has potassium, and nitrate (NO4)

EW: so if it was a mineral did it give off poisonous gases if heated?

Yes it did and so you had to be careful working around the furnaces.

So we have the tool minerals, the construction minerals, the precious metals and the base metals so far ok?

EW: ok so far

The next major metal group to develop were the ferrous ores. Iron (and steel) came into use in about 1200-1000 BC. As plain iron and low grade steel are actually poorer metals than good brass and bronze and even some coppers its not clear why the world switched from bronze to iron at that time - possibly because of an interruption in the supply of tin which would have made the bronze impossible t make so they fell back on iron. Once they had learned to work it properly it is superior to essentially all copper alloys for most purposes.

Metallurgy didn't change much from about 500 BC to about 1600 AD and neither did much if any technology as far as the earth sciences are concerned. There were a few changes in mining that were summarized by the Book De Re Metallica in the 1500's

With the advent of science in the 1600's and the development of modern chemistry in the 1800's economic geology started to expand again <G>. First was an expansion of the ferrous minerals to include nickel and cobalt and the other alloying metals.

Then the development of Aluminum and its alloys.

Then finally in the last 50 years the development of the Rare Earth and Radioactive materials industry.

Also the energy materials - coal, oil, and gas and the chemicals industry (explosives and fertilizers) - phosphates.

In actual fact there are minerals and earth materials all around you all the time. At the same time there are a group of materials and minerals that don't fit any of these classifications but that are useful in a wide variety of industries so we call these the industrial minerals. That rounds out the different groups of minerals and materials we are looking at :>

the different groups are:

Tool minerals - now known as the industrial minerals

Construction minerals and materials

Precious metals (gold, silver, and platinoids)


Base metal minerals

Ferrous minerals and materials

Aluminum minerals and materials

Energy materials

Rare earth/nuclear materials

everyone follow all that?

EW: I think we got it

En: sure

P: *nods*

Ok of these we have looked at the Aluminum and the Ferrous minerals and materials so far. So what would folks like to have next?

P: Gemstones :>


EW: that's fine with us Dad

EW: ladies first :>

P: Heh :>

Ok then we will start the gemstones next week - with the cheap end and work our way up to the real valuable ones ok?

EW: :>

P: Fine by me :>

What's that? Momma earth knows what she wants and who are we to argue?

P grins

EW: never argue we are finding out :>

P: I _can_ be argued with :>

EW: just as long as you win, right ;>

Ok Gemstones it is <G>

P wants gemstones because she just _has_ to find out about sapphires :>

And what argument did you boys lose recently with a female?

Ok and I have a whole bunch of pics of sapphires for you <G>

P: Ohhhhh :> Shinies :>

Right <G>

And I'll see if I can add some picks of some of the other sparklies <G>

Website created: January 22, 1998
Website last updated: October 11, 1998