Gift of the Ages

Story in Superior, was heating the small smoky topaz, a volcanic rock of denser quality than perlite, trying to remove the outer shell of silica, when he dropped the stone, which had been heated to an extreme temperature, into a pail of water, and an explosion took place. If further tests were made, there is no record available.

It was along about 1941, when L. Lee Boyer, metallurgical engineer, quite by accident re-discovered the expansion properties of perlite and the excitement of his discovery sent him on the way to devising some of the present processes which have made perlite available for commercial purposes.

Mr. Boyer, working in his small laboratory in Superior. was trying to find an insulating enamel. as he experimented with this volcanic glass. A small piece of perlite became involved in the experiment. and immediately started popping, in much the same manner as popcorn. He found, upon close examination, that the perlite had undergone a remarkable physical change. and had exploded into lightweight, solidified cellular glass fragments. as light as air and in all shapes and sizes. No one understood at that time what property in perlite caused it to explode. but later reports from nationally known laboratories, which had been testing the rock for moisture content established the fact that expanding was due to water and hydrogen sealed in the stone when the volcanos erupted long ago.

From then on, Mr. Boyer's enthusiasm never wavered. He built a small pilot plant at Superior immediately and started working on the theory of processing perlite through heat application of 1650 degrees F. which is less than the fusing temperature he had been using in his search for enamel. There was no guess work in his attempts now. He knew that perlite could, and would, explode when submitted to a certain temperature, and he found that after expansion the bubbles, which were walled in silica, were easily crushed. After successfully operating his pilot plant in Superior, he felt sure that he was on his way toward volume production. He then built a larger semi-commercial plant in Phoenix, Arizona, and contracted his entire output to be handled through the Duncan MacDonald agency. In talking before a meeting of engineers in Phoenix, in 1942, Mr. Boyer said: "Perlite is not a new discovery, although its application to the industries of today are considered recent. With us the problems are well past the experimental stage, as perlite has already been introduced as an industrial mineral of, perhaps, the greatest importance in its particular field of any mineral recently used. Perlite has been found superior to rock or mineral wool, vermiculite or other in-sulating materials, and because it is 100% inorganic, it is convenient and safe to handle as it is free from highly silicious and sharp particles found in rock and mineral wool. . . . Those whose interests lie in building insula-tion will find much valuable information in Government Bulletin 1-C-166 U. S. Bureau of Standards. This bulletin discourages the use of organic forms of insulation. It should be noted that perlite is a material in which termites and vermin cannot work." In explaining to the engineers the process through which he has continuously exploded or popped perlite, Mr. Boyer went on to say: "Perlite is from the Falsetic rhyolite family and very much as obsidian, however the one difference being that perlite contains hydrogen, which obsidian does not. By introducing the crude perlite into a flame and creating an excess of oxidising atmosphere through the furnace kiln, the perlite expands in 24-30 seconds, this expansion being around 700 percent in volume and resulting in a density about one-half that of ground cork."

While the idea of using perlite in the industrial field in the United States goes back only a few years, Japan found out about the rock as far back at 1929-1930. At that time S. Kosu of the Tohoku Imperial University in Japan issued a brief report on his findings, merely stating that he had found expansion properties in volcanic glass and that perlite, when heated to a critical point, would explode. Kosu, obviously did not continue his experiments, as no further mention has been made of his discovery.

Perlite deposits in Arizona range from the Black Mountains in Mohave County to the Chocolate Mountains in Yuma county, with a located deposit reported north of Winkleman in Gila county. The most important mines, however, are found at Superior, Pinal county and in western Maricopa county at Aguila, where a group of 32 claims are under lease by the Western Perlite Corporation. Both the Chemi-Cote Perlite Corporation and the Western Perlite Corporation have large holdings in the Superior area, where the largest productions of raw perlite are found. It is estimated that around 150 mining claims, aggregating tens of millions of tons of clean perlite, which can be extracted by pit mining methods, are centered in the Superior district.

The Superior deposits are ten miles in length and approximately two and one-half miles in width, running in a northwestward direction. They are located west of the copper mine at Superior and lie in a basin whose steep canyon walls, tributary to Queen Creek, reach an altitude of 4,970 feet at the top of Picket Post Mountain. Here the exposed maximum thickness of volcanic series is estimated at 1,970 feet, however only a portion of this series is made up of perlite. It is interspersed with tuff, bressia, rhyolite, and dacite with vitrophyre found at the base of the mountain.

In 1943, Mr. and Mrs. Duncan MacDonald began processing perlite on a limited scale in Phoenix, shipping the crude ore from their Superior holdings. The first years were devoted largely to research and experimentation, during which time samples of both raw and processed perlite was sent to private and government laboratories throughout the country, in an effort to discover every possible potentiality of the rock. Perlite began to assume the aspects of a miracle rock as its possibilities were determined, but Mr. MacDonald, who had spent many years as the state's leading plastering contractor, was on the trail of an element in perlite which would justify his belief that this new rock would provide a revolutionary material for plaster, stucco, building blocks and wall panels. In the beginning there was little thought of its insulative qualities nor of its acoustical properties. After months of experimental work, the perlite aggregate developed by the MacDonalds, was put on the market in wholesale quantities. It was satin-smooth, producing a pleasing wall texture, and when mixed with gypsum, the danger of checking or sweating was minimized. Frequents tests on all types of buildings were made, and it was found that in addition to the lack of visible joinings, the plaster was easily troweled. Architects tested the processed perlite for strength in building blocks, panels and beams, and enthusiastically recommended the material. Both government and private laboratories testing the processed perlite to discover its value as insulation, and with no single exception the reports of their findings gave it front ranking. A frozen food company located in Phoenix built its freezing units of perlite blocks, with an inner layer of dry perlite and an additional inside wall of the same material. The owner of the plant found that a temperature of 30 (degrees below zero was quickly reached and easily maintained in the perlite treated units, and that the operation of these perlite units were more economically operated than others. As a light weight concrete aggregate, in precasting wall boards and panels, it was found that after treatment with concrete the finished panels had the approximate weight of Douglas Fir, with the additional advantage of being sound proof, and with a perfect insulation. Radio stations and theaters began using perlite for its acoustical value and schools throughout the state have employed perlite in ceiling and wall work to sound proof their buildings. From building material the MacDonalds went on to other possible uses of perlite, and after many laboratory tests by nationally known foundations, they discovered a surprisingly wide variety of uses for this versatile product. After years of research and experimentation, designed to improve the popping process, the MacDonalds incorporated the Chemi-Cote Perlite Corporation in 1946, with distributing companies set up in Texas and California, where it is planned to have the subsidiary plants handle their own processing operations. This plan with its vast merchandishing possibilities, will bring perlite within easy reach of a rapidly growing market. The new processing plant, which is nearing completion near the Superior mine site, is located on the Magma Arizona Railroad which serves the Magma Copper Company. The past year the Chemi-Cote Perlite Corporation processed and shipped to large industries and many local businesses, more than 3,500,000 pounds of processed perlite, transporting the crude ore from their holdings in the Superior district to the Phoenix plant. Duncan MacDonald is president of the firm and his wife, Fay Young MacDonald is secretary-treasurer.

The Western Perlite Corporation, with Edward E. Swift, president and Earl F. Hastings, mining engineer, secretary-treasurer, entered the perlite field in 1946, after many months of experimental work. Hastings has made exhaustive reports on his findings, issuing them periodically through August 1943; December 1944; November 1944 and July 1946. He went carefully into the characteristics of the ore, production costs and the analysis of the whole industry as it presented itself, progressively. The reports have been constantly revised and with each revision, the conviction of Mr. Hastings and his associates grew stronger that perlite was one of the most important contributions to America's building ever to be discovered.

The Western Perlite Corporation, located in Phoenix, has a large potential capacity for processing perlite. The raw ore is shipped from Superior by rail and is processed in the Phoenix plant, which serves many large fabricators of building slabs and building blocks, plastering contractors and other concerns. The corporation's ore body is located near Thompson's Arboretum outside of Superior and contains an extensive deposit of clean, fine ore. The corporation has leases on a number of valuable perlite claims in the Aguila area, in addition to its Superior holdings.

Approximately twenty-seven perlite plants have been built in the Southwest, some of which are inoperative at this time. The Rheem Corporation becoming interested in the rock, constructed a plant in Phoenix and produced a product sold under the trade name of "Superlight." Other small plants, which have been built in the southwest include Arizona Sand and Rock Company and Williams Bros., both of Phoenix; the Alexite Company, Colorado Springs; the Cluff Plant, San Diego, Calif.; the CubanAmerican Company, Chula Vista, Calif.; Great Lakes Carbon Company in the Los Angeles area; Dantore, Portland, Oregon and the Las Vegas plant in the Las Vegas, Nevada area.

The two Phoenix corporations Chemi-Cote Perlite and Western Perlite, are the most important operating plants in the Southwest. Since the discovery that perlite could be processed through the popping method into commercial volume, the two corporations have gone untiringly on in their research and experiments. Both the Arizona Bureau of Mines and the United States Bureau of Mines have been, and are continuing to experiment with perlite, and are discovering many new uses to which the processed rock may be applied. Tests for various uses have been made by the Armour Research Foundation in Chicago; Massachusetts Institute of Technology; University of Arizona; Arizona Testing Laboratories, Phoenix; Twining Laboratories, Fresno, Calif.; Airesearch Mfg. Company, Phoenix; Department of Mineral Resources, Arizona; United Gypsum Company, Research Laboratories. A summary of the properties found in perlite, and the uses to which they have been applied, has the ring of high powered salesmanship, however every claim made for the processed material has been substantiated through authoritative sources. It long since passed its local fame, and thousands of tons of processed rock are being shipped all over the country. Scores of houses have been built of perlite and the number is increasing as fast as the material can be processed. Wherever there is heat or cold, perlite is on the job to control the temperature through its insu-lative qualities; wherever there are raucous sounds, perlite steps in to drown out the noise through its acoustical prop-erties; whatever the builder's needs-plaster, stucco, wall panels, blocks or pre-fabricated boards they are all met in perlite. The mills are turning fast today-answering the call for better houses but the perlite mills can't sup-ply the growing demand.

The tale of perlite sounds like magic. It has been found, through laboratory tests, to be one of the most suc-cessful poultry litters ever produced. Its pure inorganism, in which vermin and disease cannot breed in the pens and brooders, has given it a front ranking place with poultry growers. The fowls are kept warm and dry through the moisture absorption which reaches a point of 2:43 grams of water absorbed by 1.00 gram of perlite, thereby provid-ing quick drying for all droppings; upon removal from the pens, the litter is converted into an excellent non-packing fertilizer. Being rich in mineral content, the poultry thrive on the litter, providing as it does, a healthful grit. Ralston-Purina has tested screened perlite as a litter and found it met their requirements; for some time, Mont-gomery-Ward has handled perlite litter under the trade name of "Long-Life" handling it in their farm depart-ment; perlite has been found to make an amazingly effec-tive cleansing agent in soaps and cleaning compounds; it provides sanitary desert cooler pads; has been used by a local foundry in making cores for aluminum castings for the Goodyear Aircraft; is considered less expensive and superior to sand for molds, inasmuch as the porosity of perlite allows the gases to escape, thus preventing pits and defects; it makes an excellent bulk insulation between walls and deflects the heat of the sun, when a layer is spread on roofs. Hydroponic troughs have been made from perlite by a New Orleans concern, to be used in soil-less and refrigerators and cold boxes have been lined with perlite.

A state less balanced than Arizona would become arrogant over the great gifts which have been left within her borders. Even before man was created her needs were anticipated and when the third day of the operation got under way, and the earth buckled and groaned, the Great Planner piled up the massive heap of perlite in the Superior hills, to lie there waiting until the time should come, when man's ingenuity and man's skill would ferret out the priceless secrets of the ore.