Mineralogy

Mineralogy is an Earth Science focused around the chemistry, crystal structure, and physical (including optical) properties of minerals. Specific studies within mineralogy include the processes of mineral origin and formation, classification of minerals, their geographical distribution, as well as their utilization.

History
Early speculation, study, and theory of mineralogy was written of in ancient Babylonia, the ancient Greco-Roman world, ancient and medieval China, and noted in the prana of Sanskrit texts from ancient India. They included the Naturalis Historia of Pliny the Elder which not only described many different minerals but also explained many of their properties. Systematic scientific studies of minerals and rocks developed in post-Renaissance Europe. The credible study of mineralogy was founded on the principles of crystallography and microscopic study of rock sections with the invention of the microscope in the 17th century.

Europe and the Middle East
The ancient Greek writers Aristotle (384–322 BC) and Theophrastus (370-285 BC) were the first in the Western tradition to write of minerals and their properties, as well as metaphysical explanations for them. The Greek philosopher Aristotle wrote his Meteorologica, and in it theorized that all the known substances were composed of water, air, earth, and fire, with the properties of dryness, dampness, heat, and cold. The Greek philosopher and botanist Theophrastus wrote his De Mineralibus, which accepted Aristotle's view, and divided minerals into two categories: those affected by heat and those affected by dampness.

The metaphysical emanation and exhalation (anathumiaseis) theory of the Greek philosopher Aristotle included early speculation on earth sciences including mineralogy. According to his theory, while metals were supposed to be congealed by means of moist exhalation, dry gaseous exhalation (pneumatodestera) was the efficient material cause of minerals found in the earth's soil. He postulated these ideas by using the examples of moisture on the surface of the earth (a moist vapor 'potentially like water'), while the other was from the earth itself, pertaining to the attributes of hot, dry, smoky, and highly combustible ('potentially like fire'). Aristotle's metaphysical theory from times of antiquity had wide-ranging influence on similar theory found in later medieval Europe, as the historian Berthelot notes:

The theory of exhalations was the point of departure for later ideas on the generation of metals in the earth, which we meet with Proclus, and which reigned throughout the middle ages.

With philosophers such as Proclus, the theory of Neoplatonism also spread to the Islamic world during the Middle Ages, providing a basis for metaphyiscal ideas on mineralogy in the medieval Middle East as well. The medieval Islamic scientists expanded upon this as well, including the Persian scientist Ibn Sina (ابوعلى سينا/پورسينا‎) (980-1037 AD), who rejected alchemy and the earlier notion of Greek metaphysics that metallic and other elements could be transformed into one another. However, what was largely accurate of the ancient Greek and medieval metaphysical ideas on mineralogy was the slow chemical change in composition of the earth's crust. There was also the Islamic scientist Jabir ibn Hayyan (721-815 AD), who was the first to bring experimental method into alchemy. Aided by Greek pythagorean mathematics, he discovered the syntheses for hydrochloric acid, nitric acid, distillation, and crystallization (the latter two being essential for the understanding of modern mineralogy). Ancient Greek terminology of minerals has also stuck through the ages with widespread usage in modern times. For example, the Greek word asbestos (meaning 'inextinguishable', or 'unquenchable'), for the unusual mineral known today containing fibrous structure. The ancient historians Strabo (63 BC-19 AD) and Pliny the Elder (23-79 AD) both wrote of asbestos, its qualities, and its origins, with the Hellenistic belief that it was of a type of vegetable. Pliny the Elder listed it as a mineral common in India, while the historian Yu Huan (239-265 AD) of China listed this 'fireproof cloth' as a product of ancient Rome or Arabia (Chinese: Daqin). Although documentation of these minerals in ancient times does not fit the manner of modern scientific classification, there was nonetheless extensive written work on early mineralogy.

Pliny the Elder
For example, Pliny devoted 5 entire volumes of his work Naturalis Historia (77 AD) to the classification of "earths, metals, stones, and gems". He not only describes many minerals not known to Theophrastus, but discusses their applications and properties. He is the first to correctly recognise the origin of amber for example, as the fossilized remnant of tree resin from the observation of insects trapped in some samples. He laid the basis of crystallography by discussing crystal habit, especially the octahedral shape of diamond. His discussion of mining methods is unrivalled in the ancient world, and includes, for example, an eye-witness account of gold mining in northern Spain, an account which is fully confirmed by modern research.

However, before the more definitive foundational works on mineralogy in the 16th century, the ancients recognized no more than roughly 350 minerals to list and describe.

Georgius Agricola, 'Father of Mineralogy'


In the early 16th century AD, the writings of the German scientist Georg Bauer, pen-name Georgius Agricola (1494-1555 AD), in his Bermannus, sive de re metallica dialogus (1530) is considered to be the official establishment of mineralogy in the modern sense of its study. He wrote the treatise while working as a town physician and making observations in Joachimsthal, which was then a center for mining and metallurgic smelting industries. In 1544, he published his written work De ortu et causis subterraneorum, which is considered to be the foundational work of modern physical geology. In it (much like Ibn Sina) he heavily criticized the theories laid out by the ancient Greeks such as Aristotle. His work on mineralogy and metallurgy continued with the publication of De veteribus et novis metallis in 1546, and culminated in his best known works, the De re metallica of 1556. It was an impressive work outlining applications of mining, refining, and smelting metals, alongside discussions on geology of ore bodies, surveying, mine construction, and ventilation. He praises Pliny the Elder for his pioneering work Naturalis Historia and makes extensive references to his discussion of minerals and mining methods. For the next two centuries this written work remained the authoritative text on mining in Europe.

Agricola had many various theories on mineralogy based on empirical observation, including understanding of the concept of ore channels that were formed by the circulation of ground waters ('succi') in fissures subsequent to the deposition of the surrounding rocks. As will be noted below, the medieval Chinese previously had conceptions of this as well.

For his works, Agricola is posthumously known as the "Father of Mineralogy".

After the foundational work written by Agricola, it is widely agreed by the scientific community that the Gemmarum et Lapidum Historia of Anselmus de Boodt (1550-1632) of Bruges is the first definitive work of modern mineralogy. The German mining chemist J.F. Henckel wrote his Flora Saturnisans of 1760, which was the first treatise in Europe to deal with geobotanical minerals, although the Chinese had mentioned this in earlier treatises of 1421 and 1664. In addition, the Chinese writer Du Wan made clear references to weathering and erosion processes in his Yun Lin Shi Pu of 1133, long before Agricola's work of 1546.

China and the Far East
In ancient China, the oldest literary listing of minerals dates back to at least the 4th century BC, with the Ji Ni Zi book listing twenty four of them. Chinese ideas of metaphysical mineralogy span back to at least the ancient Han Dynasty (202 BC-220 AD). From the 2nd century BC text of the Huai Nan Zi, the Chinese used ideological Taoist terms to describe meteorology, precipitation, different types of minerals, metallurgy, and alchemy. Although the understanding of these concepts in Han times was Taoist in nature, the theories proposed were similar to the Aristotelian theory of mineralogical exhalations (noted above). By 122 BC, the Chinese had thus formulated the theory for metamorphosis of minerals, although it is noted by historians such as Dubs that the tradition of alchemical-mineralogical Chinese doctrine stems back to the School of Naturalists headed by the philosopher Zou Yan (305 BC-240 BC). Within the broad categories of rocks and stones (shi) and metals and alloys (jin), by Han times the Chinese had hundreds (if not thousands) of listed types of stones and minerals, along with theories for how they were formed.

In the 5th century AD, Prince Qian Ping Wang of the Liu Song Dynasty wrote in the encyclopedia Tai-ping Yu Lan (circa 444 AD, from the lost book Dian Shu, or Management of all Techniques):

''The most precious things in the world are stored in the innermost regions of all. For example, there is orpiment. After a thousand years it changes into realgar. After another thousand years the realgar becomes transformed into yellow gold.''

In ancient and medieval China, mineralogy became firmly tied to empirical observations in pharmaceutics and medicine. For example, the famous horologist and mechanical engineer Su Song (1020-1101 AD) of the Song Dynasty (960-1279 AD) wrote of mineralogy and pharmacology in his Ben Cao Tu Jing of 1070. In it he created a systematic approach to listing various different minerals and their use in medicinal concoctions, such as all the variously known forms of mica that could be used to cure various ills through digestion. Su Song also wrote of the subconchoidal fracture of native cinnabar, signs of ore beds, and provided description on crystal form. Similar to the ore channels formed by circulation of ground water mentioned above with the German scientist Agricola, Su Song made similar statements concerning copper carbonate, as did the earlier Ri Hua Ben Cao of 970 AD with copper sulfate.

The Yuan Dynasty scientist Zhang Si-xiao (died 1332 AD) provided a groundbreaking treatise on the conception of ore beds from the circulation of ground waters and rock fissures, two centuries before Georgius Agricola would come to similar conclusions. In his Suo-Nan Wen Ji, he applies this theory in describing the deposition of minerals by evaporation of (or precipitation from) ground waters in ore channels.

In addition to alchemical theory posed above, later Chinese writers such as the Ming Dynasty physician Li Shizhen (1518-1593 AD) wrote of mineralogy in similar terms of Aristotle's metaphysical theory, as the latter wrote in his pharmaceutical treatise Běncǎo Gāngmù (本草綱目, Compendium of Materia Medica, 1596). Another figure from the Ming era, the famous geographer Xu Xiake (1587-1641) wrote of mineral beds and mica schists in his treatise. However, while European literature on mineralogy became wide and varied, the writers of the Ming and Qing dynasties wrote little of the subject (even compared to Chinese of the earlier Song era). The only other works from these two eras worth mentioning were the Shi Pin (Hierarchy of Stones) of Yu Jun in 1617, the Guai Shi Lu (Strange Rocks) of Song Luo in 1665, and the Guan Shi Lu (On Looking at Stones) in 1668. However, one figure from the Song era that is worth mentioning above all is Shen Kuo.

Theories of Shen Kuo
The medieval Chinese Song Dynasty statesman and scientist Shen Kuo (1031-1095 AD) wrote of his land formation theory involving concepts of mineralogy. In his Meng Xi Bi Tan (梦溪笔谈; Dream Pool Essays, 1088), Shen formulated a hypothesis for the process of land formation (geomorphology); based on his observation of marine fossil shells in a geological stratum in the Taihang Mountains hundreds of miles from the Pacific Ocean. He inferred that the land was formed by erosion of the mountains and by deposition of silt, and described soil erosion, sedimentation and uplift. In an earlier work of his (circa 1080), he wrote of a curious fossil of a sea-orientated creature found far inland. It is also of interest to note that the contemporary author of the Xi Chi Cong Yu attributed the idea of particular places under the sea where serpents and crabs were petrified to one Wang Jinchen. With Shen Kuo's writing of the discovery of fossils, he formulated a hypothesis for the shifting of geographical climates throughout time. This was due to hundreds of petrified bamboos found underground in the dry climate of northern China, once an enormous landslide upon the bank of a river revealed them. Shen theorized that in pre-historic times, the climate of Yanzhou must have been very rainy and humid like southern China, where bamboos are suitable to grow.

In a similar way, the historian Joseph Needham likened Shen's account with the Scottish scientist Roderick Murchison (1792-1871), who was inspired to become a geologist after observing a providential landslide. In addition, Shen's description of sedimentary deposition predated that of James Hutton, who wrote his groundbreaking work in 1802 (considered the foundation of modern geology). The influential philosopher Zhu Xi (1130-1200) wrote of this curious natural phenomena of fossils as well, and was known to have read the works of Shen Kuo. In comparison, the first mentioning of fossils found in the West was made nearly two centuries later with Louis IX of France in 1253 AD, who discovered fossils of marine animals (as recorded in Joinville's records of 1309 AD).

Modern mineralogy
Historically, mineralogy was heavily concerned with taxonomy of the rock-forming minerals; to this end, the International Mineralogical Association is an organization whose members represent mineralogists in individual countries. Its activities include managing the naming of minerals (via the Commission of New Minerals and Mineral Names), location of known minerals, etc. As of 2004 there are over 4,000 species of mineral recognized by the IMA. Of these, perhaps 150 can be called "common," another 50 are "occasional," and the rest are "rare" to "extremely rare."

More recently, driven by advances in experimental technique (such as neutron diffraction) and available computational power, the latter of which has enabled extremely accurate atomic-scale simulations of the behaviour of crystals, the science has branched out to consider more general problems in the fields of inorganic chemistry and solid-state physics. It, however, retains a focus on the crystal structures commonly encountered in rock-forming minerals (such as the perovskites, clay minerals and framework silicates). In particular, the field has made great advances in the understanding of the relationship between the atomic-scale structure of minerals and their function; in nature, prominent examples would be accurate measurement and prediction of the elastic properties of minerals, which has led to new insight into seismological behaviour of rocks and depth-related discontinuities in seismograms of the Earth's mantle. To this end, in their focus on the connection between atomic-scale phenomena and macroscopic properties, the mineral sciences (as they are now commonly known) display perhaps more of an overlap with materials science than any other discipline.

Physical mineralogy
Physical mineralogy is the specific focus on physical attributes of minerals. Description of physical attributes is the simplest way to identify, classify, and categorize minerals, and they include:


 * crystal structure
 * crystal habit
 * twinning
 * cleavage
 * luster
 * color
 * streak
 * hardness
 * specific gravity

Chemical mineralogy
Chemical mineralogy focuses on the chemical composition of minerals in order to identify, classify, and categorize them, as well as a means to find beneficial uses from them. There are a few minerals which are classified as whole elements, including sulfur, copper, silver, and gold, yet the vast majority of minerals are comprised of chemical compounds, some more complex than others. In terms of major chemical divisions of minerals, most are placed within the isomorphous groups, which are based on analogous chemical composition and similar crystal forms. A good example of isomorphism classification would be the calcite group, containing the minerals calcite, magnesite, siderite, rhodochrosite, and smithsonite.

Biomineralogy
Biomineralogy is a cross-over field between mineralogy, paleontology and biology. It is the study of how plants and animals stabilize minerals under biological control, and the sequencing of mineral replacement of those minerals after deposition. It uses techniques from chemical mineralogy, especially isotopic studies, to determine such things as growth forms in living plants and animals as well as things like the original mineral content of fossils.

Optical mineralogy
Optical mineralogy is a specific focus of mineralogy that applies sources of light as a means to identify and classify minerals. All minerals which are not part of the cubic system are double refracting, where ordinary light passing through them is broken up into two plane polarized rays that travel at different velocities and refracted at different angles. Mineral substances belonging to the cubic system pertain only one index of refraction. Hexagonal and tetragonal mineral substances have two indices, while orthorhombic, monoclinic, and triclinic substances have three indices of refraction. With opaque ore minerals, reflected light from a microscope is needed for identification.

Crystal structure
X-rays are used to determine the atomic arrangements of minerals and so to identify and classify them. The arrangements of atoms define the crystal structures of the minerals. Some very fine-grained minerals, such as clays, commonly can be identified most readily by their crystal structures. The structure of a mineral also offers a precise way of establishing isomorphism. With knowledge of atomic arrangements and compositions, one may deduce why minerals have specific physical properties, and one may calculate how those properties change with pressure and temperature.

Formation environments
The environments of mineral formation and growth are highly varied, ranging from slow crystallization at the high temperature and pressures of igneous melts deep within the Earth's crust to the low temperature precipitation from a saline brine at the Earth's surface.

Various possible methods of formation include:


 * sublimation from volcanic gases
 * deposition from aqueous solutions and hydrothermal brines
 * crystallization from an igneous magma or lava
 * recrystallization due to metamorphic processes and metasomatism
 * crystallization during diagenesis of sediments
 * formation by oxidation and weathering of rocks exposed to the atmosphere or within the soil environment.

Uses
Minerals are essential to various needs within human society, such as minerals used for bettering health and fitness (such as mineral water or commercially-sold vitamins), essential components of metal products used in various commodities and machinery, essential components to building materials such as limestone, marble, granite, gravel, glass, plaster, cement, plastics, etc. Minerals are also used in fertilizers to enrich the growth of agricultural crops.

Descriptive mineralogy
Descriptive mineralogy summarizes results of studies performed on mineral substances. It is the scholarly and scientific method of recording the identification, classification, and categorization of minerals, their properties, and their uses. Classifications for descriptive mineralogy includes:


 * native elements
 * sulfides
 * oxides and hydroxides
 * halides
 * carbonates, nitrates and borates
 * sulfates, chromates, molybdates and tungstates
 * phosphates, arsenates and vanadates
 * silicates
 * organic minerals

Determinative mineralogy
Determinative mineralogy is the actual scientific process of identifying minerals, through data gathering and conclusion. When new minerals are discovered, a standard procedure of scientific analysis is followed, including measures to identify a mineral's formula, its crystallographic data, its optical data, as well as the general physical attributes determined and listed.