CLASSIFICATION OF ECONOMIC MINERALS
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
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
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
EW: so if it was a mineral did it give off poisonous gases if
Yes it did and so you had to be careful working around the
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
Rare earth/nuclear materials
everyone follow all that?
EW: I think we got it
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?
P: Fine by me :>
What's that? Momma earth knows what she wants and who are we to
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
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 :>
And I'll see if I can add some picks of some of the other