World of the Rockhound; 16

So we have a terrific piece materials. That man has developed and used since the beginning of time. The second largest craft hobby in America today is said to be rock hounding with all of its branches of interest some of which I jam cutting making jewelry and the collection of gem stones rocks minerals and fossils. This universal hobby has grown to astonishing proportions in the last 25 years. And shows signs of even more rapid growth as the need develops for more people to pursue more leisure time activities. Due to the fact that they are working fewer hours have more days off and get more vacation time. Rocks and minerals a specimen of extreme importance to the rock. However most people do not realize the

important role rocks and minerals play in everyday living. For example fluoride used in toothpaste and clothing. This series of programs is designed to give an overall picture of the rockhound. Offer encouragement to the newcomer in this hobby. And present information of general interest to everyone. All of this will be examined as we explore the world of the rock out. Of. Today's programme is entitled minerals all around us today and yesterday. The narrator is Len folk. And has always been surrounded by rocks and minerals so much so that a great many of these are taken for granted. And these materials as we see them have progressed so far from their original state that they are often unrecognized and their sources forgotten are not even known by the casual observer. For

some thoughts from past to present we talk with museum director feel break out. And later continuing on this subject but from a different viewpoint we talked geology professor Dr. Tom Wilcox both of these men came originally from New Jersey and both are now residents of Nashville Tennessee. In addition to being director of Nashville's Children's Museum Mr. Crouch is an artist and sculptor every day in his work he sees much evidence of man's early uses of rocks and minerals. Mr. Kraft I think one of the fascinating things that we sometimes come across and I every day life and sometimes don't realize the value of some of the natural resources that we have around us that man used since the beginning of time when you consider way back in the caveman he probably

picked up two rocks and bang them together to break not take three nuts or something like that or to mash grain and that way he found that he could use these rocks as a. Get way of gathering food or even Then again he fashioned the sticks and made clubs or axes and to cut down trees and do all the things with the rocks. I guess caveman would be considered the first rock bands wouldn't that that's right and they sort of rock because I guess they lived within their own environment that caves in practically everything they had. They use rock in some way or nothing. Yes I think so. Another material that they found to help them was the common clay. I believe the first discovery of clay was from Cave men building a fire and they found that it hardened the earth underneath the fire and he found that by taking this earth or clay as we know it today and

forming it in fashioning it into both he could make utensils in order to hold the grain or the food items that he found. And then in further use of rocks he probably found that some rocks were harder than others. In other words we found flint which he used to make his owl and spear points which he used for hunting. And of course the plant is something that the arrow heads the children find all around us today and the vast amounts of plant. That was used for Al and spear points is simply amazing. And you realize that if it wasn't for this I suppose the Indians would have found something else but Flint left a big impression on the early life of the Indian and I think to follow when they found someone had something harder. There again they found it in their own fire pot was copper or somehow melted into copper and they used this to

make implements and decorative beadwork or bracelets or something like that and there has been even some copper arrow points and spear points. So we find that man and is living in experimenting with these natural resources found one thing after another. I think Glass was a decision another discovery by the early Indians. Making a fire on probably a quartz. Sand bank of a stream. They found underneath the bed was a sort of molten Congo of. Glass like material and quartz sand and. Of course they didn't perfect that too much in too many many many years later. But that was one of the things that they found which was I think very very interesting. There are numerous other. Natural resources in the Rock and. Mineral area that we don't think too much about today but it's common in everyday use

limestone of course is a tremendous material that is used in cement and glass manufacturing and of course building and roads. If it wasn't for Limestone I don't know where Tennessee would be because Tennessee of course is known for its vast limestone. Deposits and quartz is another area which I mentioned earlier if it wasn't for the vast deposits of this quartz sand. We probably wouldn't have somebody like Ford Motor Company because this is why they came here was this discovery of the vast amounts of quartz which they use to make glass. Which we use in homes and automobiles and everyday living. And of course we can't forget Cole. I'm sort of jumping around here because of course certainly it came first before her glass and saying but in east Tennessee. Has been used to keep man warm and comfortable almost since the beginning of time so we rarely find. Many many things that.

Are. Tremendously useful and part of our every day life. Gypsum and this is another thing this comes from West Tennessee watch gypsum used for well everybody has plaster walls or plaster board or they've used plaster of paris and making casts of different things. And of course that's a building material and Tennessee has a great amount of copper that I mentioned earlier. Tennessee leads all Southern states in the mining of copper for making wire and tubing and electrical. Parts and so forth. What about you know. Do you know what goes the good china dishes Eric West Tennessee ball clay. This common clay that we get in our backyard that rough Clay is used to make brick and of course we all know what the brick industry here means

to Nashville in this area. The finer parts of clay the refined clays that West Tennessee ball clay that material is shipped all over the world are making finer dishes porcelain. Ceramic. Everything including your kitchen sink is made out of ceramic of course and. You might think that your kitchen sink today is made of metal. It's a cast you know Cast Steel form but its surface is a mammal and that is a Calais. Gotten from my own surrounding area. You being an artist do you know anything about taking man to make the colors in the painting. Yes since the beginning of time most artists found that they use different colors as we turn different clays again and different

other minerals and grinding them up and mixing them with. Some sort of a body to hold them some people of the old early days use a quite and many other different materials as a as a body to hold the material together. And this was the job of the early apprentices. Many of our famous painters they had the job of taking. Crude clays and Earths and other minerals and grinding them and grinding them and grinding them together to make a very fine paste which artists used to make paints. I guess a great many of those apprentices had to go out and hunt for the material. Yes indeed I can remember I believe it was an article in a book of Leonardo da Vinci's that he spent some time in the country finding different. Commodities paints here in our own Tennessee we have by right or bare I guess I'm not quite sure the pronunciation. That's from Monroe County and they use that as a body of paints

and also insecticides. When the insect decided what it is yes the body of a great many of the and insecticide is a mineral. A lot of your dusting powders that you use on your rose bushes of course is a very fine powder from a mineral. I don't know whether it's by right per se but it is a fine powder like a talcum that gets on the bodies of insects and gives them a hard time I guess another material that I didn't forget. Box site from Hamilton County. This is a great deal when making aluminum and of course everybody has aluminum pots and pans and aluminum. Screens on their windows which reminds me I've got to fix my screens and aluminum framing for door frames and window frames and so forth they're all made of

aluminum a great deal of bloom and it's made. Partly from oxide of course and a combination of other materials and to think back to as I mentioned Clay earlier as a. Material that our Indians used to make their pots and then again into making fine. Ceramic pieces. There again the artists use the Calais as a model to model their. Pieces which were then later cast in copper and bronze. This this material of course was used since the very beginning of time by Gyptian and even our Ben and African people in South Africa did a great deal of what we call a lost wax casting. In copper and bronze and again was. From models made in clay. So we have a terrific use of these materials. That man has developed and used since the beginning of time.

That was Mr. Philbrick M. Crouch director of the Children's Museum of Nashville commenting on man's past and present use of some minerals. A great many of them found in Tennessee originally the process of discovering the minerals and putting them to use was simply a matter of collecting through the years this of course is changed. However we still rely heavily on the natural processes. According to Dr. Tom Wilcox assistant professor of geology at Vanderbilt University who has done much research in the field of economic geology. Through the efforts of man it is now possible to extract that you will and usable materials from sources which at one time would have been considered waste materials. Take for example copper as discussed previously by Mr Crouch early man used this for his spear points and for ornaments and tools. However with this implements he was able actually to extract very little of this from the earth as

compared to modern man with his scientific knowledge and equipment. Here Dr. Wilcox discusses some of these modern methods. The subject of my. Main interest is that it is economic geology or the geology of mineral deposits about the same thing. And the main point that I would like to make today is that. In some ways contrary to what we many people think we still rely on a very heavily very extensively on. Natural processes to upgrade the concentrations of minerals or elements that we need to use in our modern technological society. It's true that the our technology has progressed a long long way

out of our technology of extracting metals and nonmetallic minerals from rocks. It has come such a long way with an engineering accomplishments that we do indeed extract metals and minerals from rocks today that would have been considered waste just a few years ago. Perhaps one of the most spectacular examples here is the extraction of copper from copper ores. At the turn of the century mining men wouldn't have dreamed of mining rock with less than oh perhaps 5 or 10 percent copper in it. Anything with a mere two or three or four percent copper would have been waste rock. And then along around the First World War why there was a sudden spurt of progress and we began mining rock with as little as 2 percent copper and iron that was then considered very very low grade ore it was considered quite a feat to be able to work it at a profit. Nowadays mining men would love to be able to

find deposits that it were that we mined rock with as little as half a percent or two thirds of one percent of copper. That's something like. 10 15 pounds of copper and a ton of rock. This is the kind of rock are working today. Well this is what I mean by the progress that we've made and in being able to treat relatively low grade materials today. In order to extract useful minerals from them. But the main point is that even so we are still using rocks extracting minerals and metals from rocks that represent tremendous natural concentrations above the average concentration of for a given metal. Let's look at some examples some of the most common metallic elements in the crust two of two of the most common

elements in the crossed are aluminum and iron ruminant represents about 8 percent of the earth's crust. And we mined aluminum ores box side ores that have that represent perhaps a four or five fold concentration above this 8 percent. We might work aluminum ores that have 30 40 percent aluminum. Iron ores and iron make up about 5 percent of the crust of the earth. We can work iron ores with as little as perhaps about 30 percent iron. So this means that we rely on nature to give us about a six fold concentration above the average for all rocks. These are relatively low multiples our concentration factors for aluminum and iron because they're such abundant metals. If we go to some of the rare metals like copper or zinc where the average bunch is measured in parts per million we start relying on

nature to give us concentrations of 100 fold or several hundred fold above the average. In the case of the copper the average is about 55 parts of copper in a million parts. That is a very tiny fraction of 1 percent. And since we need about a half of 1 percent before we can begin to think of it as copper or why. This means about 100. Fold concentration above the average. When you speak of the crust. Exactly what are you referring to half hour does the crust expand under the earth under the surface. OK. The crust is probably just what how much of the earth is the crust of the earth is a problem in itself but we. Generally we're talking about a a layer a fairly thin layer that is perhaps 20 miles thick under the continental

areas. And perhaps more like five miles under the ocean's crust as well agreed now to be thin under the oceans and thicker under the continents. Some people call the analogy of the continents being like corks floating in a city and this this is a useful way to imagine the crust in a way. Crust becomes deeper into the continents just as a large part of a cork or floating iceberg is underneath the water as well as sticking up above the water. But something like five miles of the ocean is 20 miles under the conference's is reasonable. Has anybody ever as deep as this 20 they have the crust. No that's. The fact is that mine's the deepest of our minds. I think I believe I'm correct in saying these are some of the gold mines in South Africa. Go down about two miles or a little over two miles through this crossed. So that's only only we're only talking about the outer 10

percent of this cross dissolve but we have sampled by mining now oil wells have done somewhat better for us and they give us samples from something like five miles perhaps six miles down through this crossed. But that still leaves most of the most of the crust under the continents completely seen by human eyes yet how do they know what's beneath them. That's a fair question. Yeah I made a claim that we know how thick it is and then say we've never seen it. And there is an answer to that. We have pretty reliable evidence from seismic waves. We know quite a bit about the. What causes seismic waves to behave the way they do and they get reflected back to the surface of the earth from this base of the crust that I speak of and by these reflections of seismic waves we can get at this

position or this depth to the base of the crust. After establishing that the crust of the earth we went on to discuss lead and go. Just skip to some metals that require tremendous concentration Let's take lead for example. Let's actually a fairly rare element much rarer than we're sometimes inclined to think. There are only about 12 and a half parts of lead in a million parts of average drop. That's a tiny fraction of 1 percent. And since we need about oh perhaps 3 percent lead or in order for the rock to beat and or why then this means that we need about twenty five hundred times as much lead in the rock as the average rock house. It's interesting to compare led to go go as you might guess is a very rare. Element there are. There

is only about or there are only about for one thousandth of one part per million of them. Number so small it's hard to visualize of course. And yet because of the high value of gold we can work. Gold ores that are pretty low too. In fact perhaps about a quarter of an ounce of gold and a ton of rock will make in some cases will make a gold or well this represents about 2000 upgrading 2000 times concentration above the average cost of that metal. So it turns out that common metal lead in the very rare metal gold both have to be concentrated a similar degree on the order of a couple thousand times to make an ore of that metal. This this four one thousandths of one heart and a million parts that we said was the average abundance of gold in the earth's crust.

Sounds like a bullet. Not only sounds like a very very tiny percentage but it is a very very tiny percentage indeed. And yet it's interesting that if we translate that into an amount of gold in say a cubic mile of this average rocket turns up to be quite surprising how much gold that is by. Pretty straightforward arithmetic. Making a few assumptions like you're taking an average density for this or heaviness per unit of volume for this cubic mile of rock. It turns out that that for one thousandth of one part in a million parts adds up to 50 tons of gold in an average in a cubic mile of average drop. From that you might think wow 50 tons of gold many millions of dollars worth of gold and indeed it is and we all ought to be able to go out and buy an average rock like ice just finished a few minutes ago we are not about to be able to do it.

Well it turns out that the hooker is that a cubic mile of rock is more rock. Most anyone can visualize. I don't recall now the weight and tons of that comes out to be but it's in its many billions of tons of rock and so the economics of extracting that 50 tons of gold becomes very disappointing if we start looking into it. But it is there. I think you would have to think of the three dimensions and. You know how they have a right that would be. I don't know offhand what the area of metropolitan Nashville is but that would be a square mile of Nashville be a big big chunk of our area and would have to imagine that extended down into the earth. Dr Cox compared the abundance of titanium with some of these other

metals found in your. Another interesting comparison is with the metal titanium. It happens to be a much more common element than we might expect. It's about the ninth most abundant metal in the earth's crust. There night somewhere in there. Something on the order of half of one percent of the Earth's crust is as titanium. We can work well there are. There's a lot of difference and what it is in the grade that is required to make a titanium or because it depends on whether we're going to extract it from a sand or we can get along with a perhaps a 5 or 10 percent titanium content or whether we're going to get it out of hard rocks that which we sometimes do. And this requires a higher grade because of the higher expense of working hard rock. Metal that has several very valuable properties. In this day and

age it's very lightweight and yet quite strong. So that might be called a space age metal some titanium goes into airplanes and into space other space. Or I should say in a spacecraft. It is also very chemically inert metal so it goes into applications where resistance to corrosion is worth quite a bit. Well titanium. When I was trying to make here before is that although it's a fairly common metal it's still a fairly relatively expensive metal for several reasons that we have to consider any time we're thinking about the extraction of metals. For one thing there's not a very great tendency for titanium to be concentrated. It turns out that some of these elements are very readily readily very readily undergo these concentrations required and others tend to remain dispersed in

nature and titanium is one that tends to remain dispersed it instead of forming minerals of its own although it sometimes does that it tends to remain dispersed in other minerals that are of the common rock forming minerals. Titanium might make up a fraction of a percent or a small or a few percent of very ordinary minerals. Instead of segregating into titanium oxide minerals that would represent this concentration of titanium. A. Why won't the economic geologist is often very much concerned with a start in the rules that determine the degree the extent to which metals and metallic. Minerals tend to be concentrated and also the process of the geologic processes that cause these concentrations. It's easily seen that it takes a lot of rock to yield a small percentage of any of the materials

which we see around us today. As Dr. Wilcox has mentioned this is a primary concern of the economic geologist. No doubt this concern is far removed from early man and his relationship with his surrounding rocks and minerals. For this look at rocks and minerals past and present we wish to thank Dr. Tom Wilcox assistant professor of geology at Vanderbilt University and Mr. Faber GAM Crouch director of the Children's Museum of Nashville Tennessee. This has been another in the series of programs exploring the world of the rock. The narrator was Len. This series is produced by the service of the public library of Nashville and Davidson County and Nashville Tennessee.

Next week Mrs. Vulpes will discuss the fascinating aspects of this hobby on a program entitled publications and journalism. This is Charles Michel. This is in our national educational radio network.