Encyclopedia of Glass Science, Technology, History, and Culture. Группа авторов

Figure 1 Obsidian core found in the sixth to fifth millennia BCE Aknashen Neolithic site in Armenia. As indicated by the flake scars, large flakes were detached in a single final strike by an experienced stone knapper.

      Source: Photo P. Richet.

1 A Historical Random Walk

      1.1 The Glass Age

“Among the so many, so varied products, which attest to the industrial genius of mankind, there are very few that have uses as numerous as glass, whose properties are so wonderful,” pointed out in 1868 Georges Bontemps (1799–1883), a famous nineteenth‐century glassmaker [1], who added: “no matter could replace glass in the most important of its uses.” At the same time, the great popularizer Louis Figuier (1818–1894) stated that it would be too long to list “the services that glass provides to science, the arts, industry, domestic needs, to the individual acts of man in society, to the poor and the rich, to the ignorant and to the learned.” Stressing that “household economics, science, civilization, progress and well‐being, we owe almost all this to glass,” Figuier concluded that “born with primitive societies, glass will only disappear with civilization” [2].

      Certainly, Bontemps and Figuier could not have guessed that organic polymers known as plastics would replace mineral glass in some of its traditional uses. Ironically, however, not only has mineral glass found many more, such as light guide in optical fibers (Chapter 6.4) or scaffold for bone regeneration (Chapter 8.4) to name only two of the latest, but most organic polymers are also glasses in the physical sense of the term. Since its very first origins, the vitreous state has thus opened astonishing ways to create original materials, to satisfy the most diverse needs and even to discover the world at large.

      Unlike other well‐established materials, glass has gone through more developments in the past 50 years than in two millennia from both industrial and technological standpoints. Whether overwhelming in the glazing of skyscrapers or hidden in telecommunication networks, glass has become still more ubiquitous in the modern environment than at Bontemps and Figuier's time so that claiming that we are now living in the Glass Age is not an overstatement [3, 4]. Whereas original glass compositions have, for instance, been designed for innovative lighting, screen, and display applications (Chapters 6.9 and 6.10), even the traditional products used for glazing and containers are now taking advantage of various new functionalities (Chapters 6.7 and 6.8). But what might be the most fascinating modern feature of glass is the way in which the material can be engineered to satisfy the most opposite requirements. Long celebrated for light transmission (Chapter 6.1), glass can be made opaque to a wide range of electromagnetic radiations from infrared to X‐ray wavelengths through addition of appropriately absorbing elements (Chapters 3.13 and 6.2). Chemical inertness is another major traditional asset of glass, which is in contrast purposely avoided in water glass (Chapter 7.5) and bioactive glasses (Chapter 8.4) whose usefulness rests on their intrinsically high chemical reactivity. And whereas extremely low impurity levels are required in optical fibers and other optoelectronic devices (Chapters 6.3–6.6), storage of municipal and nuclear waste relies on the capacity of glass matrices to incorporate large amounts of a great many elements (Chapters 9.10 and 9.11).

      Additional examples are not needed here to illustrate further the point as they will be found in numbers in the Encyclopedia. It is more appropriate to stress that most of these engineering developments have relied on the improved understanding of the glassy state brought by a better knowledge of its physical, chemical, and structural properties. What a long way has therefore been traveled since man made acquaintance with a strange, dark rock differing from all others by its luster and especially, when split into pieces, by its extremely sharp edges that even flint could not match!

      1.2 An Economic Forerunner

Obsidian (Figure 1), a natural glass found in volcanic provinces in various parts of the Earth, has been known from time immemorial. From arrowheads (Figure 2) to blades of any kinds and purposes (Figure 3), its unique properties made it so valuable to hunter‐gatherers that it was the very first item to be extensively exchanged over long distances [5]. Well before any man‐made object was produced, obsidian thus embodied at an early stage of human evolution the economic notion of competitive advantage, which eventually resulted in its real trade (Chapter 10.1). At the heart of a dynamic corridor between Eurasia and Africa, present‐day Armenia played a significant role in this history as a material source for a wide area in the Near East, initially through moving communities that were carrying their tools with them [6]. Armenia is also important because of the new light it has recently shed on the far‐reaching issue of the expansion of archaic Homo sapiens out of Africa.