Minerals

“ Nearly all the minerals we know of contain oxygen as a necessary ingredient, there being only a very few minerals in which that gas does not occur in chemical union with other elements. Three of these minerals, sulphur, the diamond, and graphite, consist of simple substances, and are of great commercial importance, but none of them is of so frequent occurrence, as a rock constituent, as the minerals presently to be described. ”

“ MINERALOGY, the science which describes and classifies the different kinds of mineral matter constituting the material of the earth’s crust and of those extra-terrestrial bodies called meteorites. The study of minerals is thus a branch of natural history, but one in which certain of the exact sciences find an application. The determination of the composition and constitution of minerals is a chemical problem ”

“ The 'mixed' minerals, which are composed of those same simple minerals, differ from the 'compounds', in that the simple minerals each preserves its own form so that they can be separated one from the other not only by fire but sometimes by water and sometimes by hand. ”

“ Each mineral has its own characteristic internal structure and other properties. At ordinary temperatures, nearly all the minerals are solids rather than gases or liquids. (Water and mercury are the principal exceptions.) In addition, minerals are inorganic rather than being composed of plant or animal matter. ”

“ Missing from the lists of the most abundant minerals and rocks, are the greater part of the commercially important mineral resources—including such as coal, oil, gas, iron ore, copper, gold, and silver,—implying that these mineral products, notwithstanding their great absolute bulk and commercial importance, occur in relatively insignificant amounts as compared with the common rock minerals of the earth. ”

“ My purpose in calling attention to this point is simply to suggest that the proper way to begin the study of minerals and rocks with children is to first familiarize them with the elements of which they are composed. The most important thing to be known about any mineral is its chemical composition; and when a child is told that a mineral—corundum, for example—is composed of oxygen and aluminum, he should have a distinct conception of the properties of each of those elements, for otherwise corundum is for him a mere compound of names. ”

“ MINERAL KINGDOM, an expression comprising all bodies that are dug out of subterraneous places, or mines, being totally inanimate, and devoid of the power of vegetation.
From the preceding definition, it is obvious that minerals are inorganic substances which, like organized bodies, have a certain origin, progressively increase, and are subject to dissolution, or a decomposition of parts. ”

“ With slight exceptions minerals are the materials which make up the known part of the earth. In a very real sense, then, mineralogy is the most fundamental of the various branches of the great science of geology because the events of earth history, as interpreted by the geologist, are recorded in the mineral matter (including most rocks) of the earth. When we examine the rocky material or mineral matter of the earth in any region we find that it consists of various kinds of substances each of which may be recognized by certain characteristics. ”

“ We have already compared the chemical elements to the alphabet and the minerals to words. We can now go a step further and compare rocks to sentences. We put words together to make sentences; nature puts minerals together to make rocks. A sentence does not have to be made up of a definite number of words, nor does a rock have to be made up of a definite number of minerals. Some rocks, such as granite, may be composed of several minerals. Others, such as dolomite and rock gypsum, consist of only one mineral. ”

“ Minerals.—The mineral resources of the kingdom, though capable of further development, are not rich. They are chiefly confined to the mountains, where iron, coal, copper, lead, zinc, silver and sulphur are mined in small quantities. ”

“ The first are again divided into simple and compound minerals. The simple minerals are of four classes, namely earths, solidified juices, stones and metals, while the mineral compounds are of many sorts, as I shall explain later.
Earth is a simple mineral body which may be kneaded in the hands when moistened, or from which lute is made when it has been wetted. Earth, properly so called, is found enclosed in veins or veinlets, or frequently on the surface in fields and meadows. ”

“ The materials—phosphate rock, sulphur, and nitrates—used in making artificial fertilizers; the marbles; the pigment-yielding minerals, including ochres, umber, and barite; the clays, with their products of earthenware and pottery, bricks, and tiles; and even mineral waters are among the different minerals to be seen. It is from such exhibits that something of an idea is obtained of the enormous wealth that is contained in the earth, waiting only to be excavated and fashioned into articles of beauty and utility. ”

“ All substances found in the earth or upon its surface, which are not the products of art or of organic life, are regarded by the mineralogist as simple minerals. About four hundred mineral species are known, and the varieties are much more numerous ”

“ All parts of minerals are alike. There are simple minerals and mixed. The former are the true minerals, and are generally considered under the heading Mineralogy. The others constitute a branch of Geology, as they form aggregate masses, and as such compose a large portion of the earth. We must learn to distinguish minerals and crystals as inorganic forms of nature. In the animal and vegetable kingdoms we have forms which are possessed of organs of sight, smell, taste, and certain structures indispensable to their existence and development. But in minerals we have no such attributes. ”

“ When a single chemical element is found alone in nature as a solid, it is considered to be a mineral, too. Gold, silver, copper, lead, and sulfur are some of the chemical elements that can occur alone as solid minerals. When they occur this way, we refer to them as native silver, native copper, or native sulfur. Although the element mercury is a liquid rather than a solid at ordinary temperatures, it too is a mineral when it occurs alone in nature. ”

“ When not mixed with any other substances, minerals are composed of similar particles, and if they possess a definite shape, are characterized by the geometric form their crystals assume, although all minerals are not distinctly crystalline. Minerals enter into the composition of the rocks, which constitute the solid portion of our globe, and guard the land against the encroachments of the sea. ”

“ All the known chemical elements have been found in minerals; and of many of them minerals are the only source. On the other hand, nitrogen, which is frequently present in organic substances, is rare in minerals; carbon has a wide distribution in mineral carbonates. It is estimated that the minerals of the earth's crust consist of about 47% by weight of oxygen, 27 of silicon and 8 of aluminium; silicates, and especially aluminosilicates, therefore predominate, these being the more important rock-forming minerals. ”

“ Or, more specifically, a mineral is a natural, inorganic, homogeneous substance of definite chemical composition. According to this definition a mineral must be found ready made in nature, must not be a product of life, must be of the same nature throughout, and its composition must be so definite that it can be expressed by a chemical formula. All artificial substances, such as laboratory and furnace products, are excluded from the category of minerals. Coal is not a mineral because it is both organic and of indefinite composition. ”

“ The study of minerals is the most imperfect of the three branches of natural history, because, notwithstanding its apparent simplicity, and the immense number of experiments which have been made, the true method of investigation has not yet been ascertained; it being doubtful whether mineralogy ought to be subordinated to the laws of chemistry, or to those of crystallography, or whether both sets of laws will have to be considered. ”

“ However, when we refer to mineral resources or industrial minerals, we generally include materials that are technically rocks—such as limestone, dolomite, shale—and also coal and oil that are in fact organic substances. ”

“ Most classifications of minerals are based on the composition, all the sulphides, carbonates, etc., being grouped together, but in this book, because the popular interest and commercial uses are primarily in ix the metal present, the minerals are grouped in each case about the chief metal, all the minerals of iron being grouped together, for instance. ”

“ The mineral composition of rocks is greatly simplified by the wide range of conditions under which the commonest minerals can be formed. Thus quartz, feldspar, mica, the minerals of the hornblende, or pyroxene group, can be formed from a mass cooling from a state of fusion; they may be crystallized from solution, or be formed from volatilized products. They are therefore the 25commonest of minerals and are rarely excluded from rocks of any class, since there is no process of rock formation which determines their absence. ”

“ As is well known, however, igneous rocks are in some instances of value for the metallic mineral, gems, and ores associated with them, but in the great majority of instances at least, and as a rule, these minerals and ores are the result of subsequent changes and owe their origin mainly to deposition from heated, percolating water. ”

“ Other sedimentary rocks consist of minerals deposited from solution either by chemical or organic agencies, from sea-water, lakes or springs: e.g. the calcite of limestones, deposits of bog-iron-ore (limonite) , gypsum, rocksalt, &c.
Minerals Segregated in Veins and Rock-cavities.—Water percolating through rock-masses takes up mineral matter in solution, and the solutions so formed may further react on the minerals composing the rocks. ”

“ The chemical reactions by which Various minerals have been obtained are often of considerable help in speculating as to their mode of origin in nature, though it must be born in mind that the same mineral may have been formed, both naturally and artificially, by more methods than one. ”

“ Our mineralogy, however, is a treasure but just opened. That both science and art may expect much advantage from this source, is sufficiently evinced by the success which has crowned the active efforts of a few ardent cultivators of this science: several new species of minerals have been added to it in this country; great numbers of American localities discovered, and interesting additions made to our materials, for the useful and ornamental arts. The science of mineralogy is now illustrated by courses of lectures, and by several good cabinets in the different states. ”

“ Such products include coal, petroleum, natural gas, many valuable metal-bearing minerals, and many nonmetalliferous minerals and rocks. In most cases these valuable products of nature have been slowly accumulated or concentrated at many times and under widely varying conditions throughout the millions of years of known geological time. To trace the extent of, and most advantageously remove, such deposits for the use of man is always invariably impossible unless geological knowledge is brought to bear. ”

“ Besides, in considering the causes of mineral waters, it seems more probable, that whatever minerals they contain, they must be such, as can be received or extracted by common water in its passage thro' the earth, by solution, abrasion, or the like simple operations; and in this way alone I think we may come to account not only for the commixtion of the saline and terrene minerals, which are found in medical waters, but likewise of those, that are metalline or sulphureous; for which simple water, at first sight, may perhaps seem to be an insufficient solvent. ”

“ It was also stated that, if a scientific man wants to be precise, he confines his use of the term 'mineral' to a certain homogeneous substance, a chemical entity, having a definite composition, just as the mineralogist does, but nevertheless minerals are both solids and liquid, according to most definitions, and that some authorities include agses among minerals, and others exclude them. ”

“ The most important of such minerals are gold, tin, platinum, and the precious stones. Iron, copper, lead, and zinc minerals are often somewhat concentrated as placers, but their intrinsic value is not high enough to warrant the attempt to recover them in the large amounts necessary to make them commercially available. ”

“ Whereas by weathering the rock is loosened up and disintegrated, substances like carbon dioxide, oxygen, and water are abundantly added, and light minerals of simple composition tend to develop,—by dynamic metamorphism on the other hand, carbon dioxide, oxygen, and water are usually expelled, the minerals are combined to make heavier and more complex minerals, pore space is eliminated, and altogether the rock becomes much more dense and crystalline. ”

“ Iron ore, tin, copper and tungsten are extracted from the earth, refined, put to some use or wasted as the case may be, but they are gone. They may be replaced by other minerals. Through geological ages they may redeposited in the earth's crust. ”

“ To establish a general theory on the formation of Minerals, we must begin then by distinguishing with the greatest attention, first, those which have been produced by the primitive fire of the earth while it was burning with heat ”