In agriculture, a terrace is a piece of sloped plane, cut into a series of successively receding flat surfaces or platforms, which resemble steps, for the purposes of more effective farming. This type of landscaping is therefore called terracing. Graduated terrace steps are used to farm on hilly or mountainous terrain. Terraced fields decrease both erosion and surface runoff, may be used to support growing crops that require irrigation, such as rice; the Rice Terraces of the Philippine Cordilleras have been designated as a UNESCO World Heritage Site because of the significance of this technique. Terraced paddy fields are used in rice and barley farming in east and southeast Asia, as well as the Mediterranean and South America. Drier-climate terrace farming is common throughout the Mediterranean Basin, where they are used for vineyards, olive trees, cork oak, etc. In the South American Andes, farmers have used terraces, known as andenes, for over a thousand years to farm potatoes and other native crops.
Terraced farming was developed by the Wari culture and other peoples of the south-central Andes before 1000 AD, centuries before they were used by the Inca, who adopted them. The terraces were built to make the most efficient use of shallow soil and to enable irrigation of crops by allowing runoff to occur through the outlet; the Inca built on these, developing a system of canals and puquios to direct water through dry land and increase fertility levels and growth. These terraced farms are found, they provided the food necessary to support the populations of great Inca cities and religious centres such as Machu Picchu. Terracing is used for sloping terrain. At the seaside Villa of the Papyri in Herculaneum, the villa gardens of Julius Caesar's father-in-law were designed in terraces to give pleasant and varied views of the Bay of Naples. Terraced fields are common in islands with steep slopes; the Canary Islands present a complex system of terraces covering the landscape from the coastal irrigated plantations to the dry fields in the highlands.
These terraces, which are named cadenas, are built with stone walls of skillful design, which include attached stairs and channels. In Old English, a terrace was called a "lynch". An example of an ancient Lynch Mill is in Lyme Regis; the water is directed from a river by a duct along a terrace. This set-up was used in steep hilly areas in the UK. In Japan, some of the 100 Selected Terraced Rice Fields, from Iwate in the north to Kagoshima in the south, are disappearing, but volunteers are helping the farmers both to maintain their traditional methods and for sightseeing purposes. Anden Banaue Rice Terraces Rice Terraces of the Philippine Cordilleras Satoyama Terrace garden Terrace Fields around the World
Basalt is a mafic extrusive igneous rock formed from the rapid cooling of magnesium-rich and iron-rich lava exposed at or near the surface of a terrestrial planet or a moon. More than 90% of all volcanic rock on Earth is basalt. Basalt lava has a low viscosity, due to its low silica content, resulting in rapid lava flows that can spread over great areas before cooling and solidification. Flood basalt describes the formation in a series of lava basalt flows. By definition, basalt is an aphanitic igneous rock with 45–53% silica and less than 10% feldspathoid by volume, where at least 65% of the rock is feldspar in the form of plagioclase; this is as per definition of the International Union of Geological Sciences classification scheme. It is the most common volcanic rock type on Earth, being a key component of oceanic crust as well as the principal volcanic rock in many mid-oceanic islands, including Iceland, the Faroe Islands, Réunion and the islands of Hawaiʻi. Basalt features a fine-grained or glassy matrix interspersed with visible mineral grains.
The average density is 3.0 g/cm3. Basalt is defined by its mineral content and texture, physical descriptions without mineralogical context may be unreliable in some circumstances. Basalt is grey to black in colour, but weathers to brown or rust-red due to oxidation of its mafic minerals into hematite and other iron oxides and hydroxides. Although characterized as "dark", basaltic rocks exhibit a wide range of shading due to regional geochemical processes. Due to weathering or high concentrations of plagioclase, some basalts can be quite light-coloured, superficially resembling andesite to untrained eyes. Basalt has a fine-grained mineral texture due to the molten rock cooling too for large mineral crystals to grow; these phenocrysts are of olivine or a calcium-rich plagioclase, which have the highest melting temperatures of the typical minerals that can crystallize from the melt. Basalt with a vesicular texture is called vesicular basalt, when the bulk of the rock is solid; this texture forms when dissolved gases come out of solution and form bubbles as the magma decompresses as it reaches the surface, yet are trapped as the erupted lava hardens before the gases can escape.
The term basalt is at times applied to shallow intrusive rocks with a composition typical of basalt, but rocks of this composition with a phaneritic groundmass are referred to as diabase or, when more coarse-grained, as gabbro. Gabbro is marketed commercially as "black granite." In the Hadean and early Proterozoic eras of Earth's history, the chemistry of erupted magmas was different from today's, due to immature crustal and asthenosphere differentiation. These ultramafic volcanic rocks, with silica contents below 45% are classified as komatiites; the word "basalt" is derived from Late Latin basaltes, a misspelling of Latin basanites "very hard stone", imported from Ancient Greek βασανίτης, from βάσανος and originated in Egyptian bauhun "slate". The modern petrological term basalt describing a particular composition of lava-derived rock originates from its use by Georgius Agricola in 1556 in his famous work of mining and mineralogy De re metallica, libri XII. Agricola applied "basalt" to the volcanic black rock of the Schloßberg at Stolpen, believing it to be the same as the "very hard stone" described by Pliny the Elder in Naturalis Historiae.
Tholeiitic basalt is rich in silica and poor in sodium. Included in this category are most basalts of the ocean floor, most large oceanic islands, continental flood basalts such as the Columbia River Plateau. High and low titanium basalts. Basalt rocks are in some cases classified after their titanium content in High-Ti and Low-Ti varieties. High-Ti and Low-Ti basalts have been distinguished in the Paraná and Etendeka traps and the Emeishan Traps. Mid-ocean ridge basalt is a tholeiitic basalt erupted only at ocean ridges and is characteristically low in incompatible elements. E-MORB, enriched MORB N-MORB, normal MORB D-MORB, depleted MORB High-alumina basalt may be silica-undersaturated or -oversaturated, it has greater than 17% alumina and is intermediate in composition between tholeiitic basalt and alkali basalt. Alkali basalt is poor in silica and rich in sodium, it may contain feldspathoids, alkali feldspar and phlogopite. Boninite is a high-magnesium form of basalt, erupted in back-arc basins, distinguished by its low titanium content and trace-element composition.
Ocean island basalt Lunar basalt The mineralogy of basalt is characterized by a preponderance of calcic plagioclase feldspar and pyroxene. Olivine can be a significant constituent. Accessory minerals present in minor amounts include iron oxides and iron-titanium oxides, such as magnetite and ilmenite; because of the presence of such oxide minerals, basalt can acquire strong magnetic signatures as it cools, paleomagnetic studies have made extensive use of basalt. In tholeiitic basalt and calcium-rich plagioclase are common phenocryst minerals. Olivine may be a phenocryst, when
History of technology
The history of technology is the history of the invention of tools and techniques and is one of the categories of the history of humanity. Technology can refer to methods ranging from as simple as stone tools to the complex genetic engineering and information technology that has emerged since the 1980s; the term technology comes from the Greek word techne, meaning art and craft, the word logos, meaning word and speech. It was first used to describe applied arts, but it is now used to described advancements and changes which affect the environment around us. New knowledge has enabled people to create new things, conversely, many scientific endeavors are made possible by technologies which assist humans in traveling to places they could not reach, by scientific instruments by which we study nature in more detail than our natural senses allow. Since much of technology is applied science, technical history is connected to the history of science. Since technology uses resources, technical history is connected to economic history.
From those resources, technology produces other resources, including technological artifacts used in everyday life. Technological change affects and is affected by, a society's cultural traditions, it is a force for economic growth and a means to develop and project economic, military power and wealth. Many sociologists and anthropologists have created social theories dealing with social and cultural evolution. Some, like Lewis H. Morgan, Leslie White, Gerhard Lenski have declared technological progress to be the primary factor driving the development of human civilization. Morgan's concept of three major stages of social evolution can be divided by technological milestones, such as fire. White argued. For White, "the primary function of culture" is to "harness and control energy." White differentiates between five stages of human development: In the first, people use the energy of their own muscles. In the second, they use the energy of domesticated animals. In the third, they use the energy of plants.
In the fourth, they learn to use the energy of natural resources: coal, gas. In the fifth, they harness nuclear energy. White introduced a formula P=E*T, where E is a measure of energy consumed, T is the measure of the efficiency of technical factors using the energy. In his own words, "culture evolves as the amount of energy harnessed per capita per year is increased, or as the efficiency of the instrumental means of putting the energy to work is increased". Nikolai Kardashev extrapolated his theory, creating the Kardashev scale, which categorizes the energy use of advanced civilizations. Lenski's approach focuses on information; the more information and knowledge a given society has, the more advanced. He identifies four stages of human development, based on advances in the history of communication. In the first stage, information is passed by genes. In the second, when humans gain sentience, they can pass information through experience. In the third, the humans start develop logic. In the fourth, they can develop language and writing.
Advancements in communications technology translate into advancements in the economic system and political system, distribution of wealth, social inequality and other spheres of social life. He differentiates societies based on their level of technology and economy: hunter-gatherer, simple agricultural, advanced agricultural, special. In economics, productivity is a measure of technological progress. Productivity increases. Another indicator of technological progress is the development of new products and services, necessary to offset unemployment that would otherwise result as labor inputs are reduced. In developed countries productivity growth has been slowing since the late 1970s. For example, employment in manufacturing in the United States declined from over 30% in the 1940s to just over 10% 70 years later. Similar changes occurred in other developed countries; this stage is referred to as post-industrial. In the late 1970s sociologists and anthropologists like Alvin Toffler, Daniel Bell and John Naisbitt have approached the theories of post-industrial societies, arguing that the current era of industrial society is coming to an end, services and information are becoming more important than industry and goods.
Some extreme visions of the post-industrial society in fiction, are strikingly similar to the visions of near and post-Singularity societies. The following is a summary of the history of technology by time period and geography: During most of the Paleolithic – the bulk of the Stone Age – all humans had a lifestyle which involved limited tools and few permanent settlements; the first major technologies were tied to survival and food preparation. Stone tools and weapons and clothing were technological developments of major importance during this period. Human ancestors have been using stone and other tools since long before the emergence of Homo sapiens 200,000 years ago; the earliest methods of stone tool making, known as the Oldowan "industry", date back to at least 2.3 million years ago, with the earliest direct evidence of tool usage found in Ethiopia within the Great Rift Valley, dating back to 2.5 million years ago. This era of stone tool use is called the Paleolithic
Technology is the collection of techniques, skills and processes used in the production of goods or services or in the accomplishment of objectives, such as scientific investigation. Technology can be the knowledge of techniques and the like, or it can be embedded in machines to allow for operation without detailed knowledge of their workings. Systems applying technology by taking an input, changing it according to the system's use, producing an outcome are referred to as technology systems or technological systems; the simplest form of technology is the use of basic tools. The prehistoric discovery of how to control fire and the Neolithic Revolution increased the available sources of food, the invention of the wheel helped humans to travel in and control their environment. Developments in historic times, including the printing press, the telephone, the Internet, have lessened physical barriers to communication and allowed humans to interact on a global scale. Technology has many effects, it has allowed the rise of a leisure class.
Many technological processes produce unwanted by-products known as pollution and deplete natural resources to the detriment of Earth's environment. Innovations have always influenced the values of a society and raised new questions in the ethics of technology. Examples include the rise of the notion of efficiency in terms of human productivity, the challenges of bioethics. Philosophical debates have arisen over the use of technology, with disagreements over whether technology improves the human condition or worsens it. Neo-Luddism, anarcho-primitivism, similar reactionary movements criticize the pervasiveness of technology, arguing that it harms the environment and alienates people; the use of the term "technology" has changed over the last 200 years. Before the 20th century, the term was uncommon in English, it was used either to refer to the description or study of the useful arts or to allude to technical education, as in the Massachusetts Institute of Technology; the term "technology" rose to prominence in the 20th century in connection with the Second Industrial Revolution.
The term's meanings changed in the early 20th century when American social scientists, beginning with Thorstein Veblen, translated ideas from the German concept of Technik into "technology." In German and other European languages, a distinction exists between technik and technologie, absent in English, which translates both terms as "technology." By the 1930s, "technology" referred not only to the study of the industrial arts but to the industrial arts themselves. In 1937, the American sociologist Read Bain wrote that "technology includes all tools, utensils, instruments, clothing and transporting devices and the skills by which we produce and use them." Bain's definition remains common among scholars today social scientists. Scientists and engineers prefer to define technology as applied science, rather than as the things that people make and use. More scholars have borrowed from European philosophers of "technique" to extend the meaning of technology to various forms of instrumental reason, as in Foucault's work on technologies of the self.
Dictionaries and scholars have offered a variety of definitions. The Merriam-Webster Learner's Dictionary offers a definition of the term: "the use of science in industry, etc. to invent useful things or to solve problems" and "a machine, piece of equipment, etc., created by technology." Ursula Franklin, in her 1989 "Real World of Technology" lecture, gave another definition of the concept. The term is used to imply a specific field of technology, or to refer to high technology or just consumer electronics, rather than technology as a whole. Bernard Stiegler, in Technics and Time, 1, defines technology in two ways: as "the pursuit of life by means other than life," and as "organized inorganic matter."Technology can be most broadly defined as the entities, both material and immaterial, created by the application of mental and physical effort in order to achieve some value. In this usage, technology refers to tools and machines that may be used to solve real-world problems, it is a far-reaching term that may include simple tools, such as a crowbar or wooden spoon, or more complex machines, such as a space station or particle accelerator.
Tools and machines need not be material. W. Brian Arthur defines technology in a broad way as "a means to fulfill a human purpose."The word "technology" can be used to refer to a collection of techniques. In this context, it is the current state of humanity's knowledge of how to combine resources to produce desired products, to solve problems, fulfill needs, or satisfy wants; when combined with another term, such as "medical technology" or "space technology," it refers to the state of the respective field's knowledge and tools. "State-of-the-art technology" refers to the high technology available to humanity in any field. Technology can be viewed as an activity that changes culture. Additionally, technology is the application of math, science, an
Obsidian is a occurring volcanic glass formed as an extrusive igneous rock. Obsidian is produced when felsic lava extruded from a volcano cools with minimal crystal growth, it is found within the margins of rhyolitic lava flows known as obsidian flows, where the chemical composition causes a high viscosity which, upon rapid cooling, forms a natural glass from the lava. The inhibition of atomic diffusion through this viscous lava explains the lack of crystal growth. Obsidian is hard and amorphous. In the past it was used to manufacture cutting and piercing tools and it has been used experimentally as surgical scalpel blades.... among the various forms of glass we may reckon Obsidian glass, a substance similar to the stone found by Obsidius in Ethiopia. The translation into English of Natural History written by Pliny the Elder of Rome shows a few sentences on the subject of a volcanic glass called obsidian, discovered in Ethiopia by Obsidius, a Roman explorer. Obsidian is the rock formed as a result of cooled lava, the parent material.
Extrusive formation of obsidian may occur when felsic lava cools at the edges of a felsic lava flow or volcanic dome or when lava cools during sudden contact with water or air. Intrusive formation of obsidian may occur. Tektites were once thought by many to be obsidian produced by lunar volcanic eruptions, though few scientists now adhere to this hypothesis. Obsidian is mineral-like, but not a true mineral, it is sometimes classified as a mineraloid. Though obsidian is dark in color, similar to mafic rocks such as basalt, obsidian's composition is felsic. Obsidian consists of SiO2 70% or more. Crystalline rocks with obsidian's composition include rhyolite; because obsidian is metastable at the Earth's surface, no obsidian has been found, older than Cretaceous age. This breakdown of obsidian is accelerated by the presence of water. Having a low water content when newly formed less than 1% water by weight, obsidian becomes progressively hydrated when exposed to groundwater, forming perlite. Pure obsidian is dark in appearance, though the color varies depending on the presence of impurities.
Iron and other transition elements may give the obsidian a dark brown to black color. Few samples are nearly colorless. In some stones, the inclusion of small, radially clustered crystals spherulites of the mineral cristobalite in the black glass produce a blotchy or snowflake pattern. Obsidian may contain patterns of gas bubbles remaining from the lava flow, aligned along layers created as the molten rock was flowing before being cooled; these bubbles can produce interesting effects such as a golden sheen. An iridescent, rainbow-like sheen is caused by inclusions of magnetite nanoparticles. Obsidian can be found in locations, it can be found in Argentina, Azerbaijan, Canada, Georgia, Greece, El Salvador, Iceland, Japan, Mexico, New Zealand, Papua New Guinea, Scotland and the United States. Obsidian flows which may be hiked on are found within the calderas of Newberry Volcano and Medicine Lake Volcano in the Cascade Range of western North America, at Inyo Craters east of the Sierra Nevada in California.
Yellowstone National Park has a mountainside containing obsidian located between Mammoth Hot Springs and the Norris Geyser Basin, deposits can be found in many other western U. S. states including Arizona, New Mexico, Utah, Washington and Idaho. Obsidian can be found in the eastern U. S. states of Virginia, as well as North Carolina. There are only four major deposit areas in the central Mediterranean: Lipari, Pantelleria and Monte Arci. Ancient sources in the Aegean were Gyali. Acıgöl town and the Göllü Dağ volcano were the most important sources in central Anatolia, one of the more important source areas in the prehistoric Near East; the first known archaeological evidence of usage was in Kariandusi and other sites of the Acheulian age dated 700,000 BC, although the number of objects found at these sites were low relative to the Neolithic. Use of obsidian in pottery of the Neolithic in the area around Lipari was found to be less at a distance representing two weeks journeying. Anatolian sources of obsidian are known to have been the material used in the Levant and modern-day Iraqi Kurdistan from a time beginning sometime about 12,500 BC.
The first attested civilized use is dated to the late fifth millennium BC, known from excavations at Tell Brak. Obsidian was valued in Stone Age cultures because, like flint, it could be fractured to produce sharp blades or arrowheads. Like all glass and some other types of occurring rocks, obsidian breaks with a characteristic conchoidal fracture, it was polished to create early mirrors. Modern archaeologists have developed a relative dating system, obsidian hydration dating, to calculate the age of obsidian artifacts. In the Ubaid in the 5th millennium BC, blades were manufactured from obsidian extracted from outcrops located in modern-day Turkey. Ancient Egyptians used obsidian imported from the eastern Mediterranean and southern Red Sea regions. Obsidian was used in ritual circumcisions because of its deftness and sharpness. In the eastern Mediterranean
An axe is an implement, used for millennia to shape and cut wood, to harvest timber, as a weapon, as a ceremonial or heraldic symbol. The axe has many forms and specialised uses but consists of an axe head with a handle, or helve. Before the modern axe, the stone-age hand axe was used from 1.5 million years BP without a handle. It was fastened to a wooden handle; the earliest examples of handled axes have heads of stone with some form of wooden handle attached in a method to suit the available materials and use. Axes made of copper, bronze and steel appeared as these technologies developed. Axes are composed of a head and a handle; the axe is an example of a simple machine, as it is dual inclined plane. This reduces the effort needed by the wood chopper, it splits the wood into two parts by the pressure concentration at the blade. The handle of the axe acts as a lever allowing the user to increase the force at the cutting edge—not using the full length of the handle is known as choking the axe. For fine chopping using a side axe this sometimes is a positive effect, but for felling with a double bitted axe it reduces efficiency.
Cutting axes have a shallow wedge angle, whereas splitting axes have a deeper angle. Most axes are double bevelled, i.e. symmetrical about the axis of the blade, but some specialist broadaxes have a single bevel blade, an offset handle that allows them to be used for finishing work without putting the user's knuckles at risk of injury. Less common today, they were once an integral part of a joiner and carpenter's tool kit, not just a tool for use in forestry. A tool of similar origin is the billhook. Most modern axes have steel heads and wooden handles hickory in the US and ash in Europe and Asia, although plastic or fibreglass handles are common. Modern axes are specialised by use and form. Hafted axes with short handles designed for use with one hand are called hand axes but the term hand axe refers to axes without handles as well. Hatchets tend to be small hafted axes with a hammer on the back side; as easy-to-make weapons, axes have been used in combat. Axes were tools of stone called hand axes, used without handles, had knapped cutting edges of flint or other stone.
Stone axes made with ground cutting edges were first developed sometime in the late Pleistocene in Australia, where ground-edge axe fragments from sites in Arnhem Land date back at least 44,000 years. In Europe, the innovation of ground edges occurred much in the Neolithic period ending 4,000 to 2,000 BC; the first true hafted axes are known from the Mesolithic period. Few wooden hafts have been found from this period, but it seems that the axe was hafted by wedging. Birch-tar and raw-hide lashings were used to fix the blade. Sometimes a short section of deer antler was used, which prevented the splitting of the haft and softened the impact on the stone blade itself, helping absorb the impact of each axe blow and lessening the chances of breaking the handle; the antler was hollowed out at one end to create a socket for the axehead. The antler sheath was either perforated and a handle inserted into it or set in a hole made in the handle instead; the distribution of stone axes is an important indication of prehistoric trade.
Thin sectioning is used to determine the provenance of the stone blades. In Europe, Neolithic "axe factories", where thousands of ground stone axes were roughed out, are known from many places, such as: Great Langdale, England Rathlin Island, Ireland Krzemionki, Poland Plancher-les-Mines, France Aosta Valley, Italy. Stone axes are still in use today in parts of Papua, Indonesia; the Mount Hagen area of Papua New Guinea was an important production centre. From the late Neolithic/Chalcolithic onwards, axes were made of copper mixed with arsenic; these axes were hafted much like their stone predecessors. Axes continued to be made in this manner with the introduction of Bronze metallurgy; the hafting method changed and the flat axe developed into the "flanged axe" palstaves, winged and socketed axes. The Proto-Indo-European word for "axe" may have been *pelek'u-, but the word was a loan, or a Neolithic wanderwort related to Sumerian balag, Akkadian pilaku-. At least since the late Neolithic, elaborate axes had a religious significance and indicated the exalted status of their owner.
Certain types never show traces of wear. In Minoan Crete, the double axe had a special significance, used by priestesses in religious ceremonies; the symbol refers to deification ceremonies. In 1998 a labrys, complete with an elaborately embellished haft, was found at Cham-Eslen, Canton of Zug, Switzerland; the haft wrapped in ornamented birch-bark. The axe blade is 17.4 cm long and made of antigorite, mined in the Gotthard-area. The haft is fastened by wedges of antler and by birch-tar, it belongs to the early Cortai
Mortar and pestle
Mortar and pestle are implements used since ancient times to prepare ingredients or substances by crushing and grinding them into a fine paste or powder in the kitchen and pharmacy. The mortar is a bowl made of hard wood, ceramic, or hard stone, such as granite; the pestle is a blunt club-shaped object. The substance to be ground, which may be wet or dry, is placed in the mortar, where the pestle is pressed and rotated onto it until the desired texture is achieved. Scientists have found ancient mortars and pestles that date back to 35000 BC; the English word mortar derives from classical Latin mortarium, among several other usages, "receptacle for pounding" and "product of grinding or pounding". The classical Latin pistillum, meaning "pounder", led to English pestle; the Roman poet Juvenal applied both mortarium and pistillum to articles used in the preparation of drugs, reflecting the early use of the mortar and pestle as a symbol of a pharmacist or apothecary. The antiquity of these tools is well documented in early writing, such as the Egyptian Ebers Papyrus of ~1550 BC and the Old Testament.
Mortars and pestles were traditionally used in pharmacies to crush various ingredients prior to preparing an extemporaneous prescription. The mortar and pestle, with the Rod of Asclepius, the Green Cross, others, is one of the most pervasive symbols of pharmacology, along with the show globe. For pharmaceutical use, the mortar and the head of the pestle are made of porcelain, while the handle of the pestle is made of wood; this is known as a Wedgwood mortar and pestle and originated in 1759. Today the act of reducing the particle size is known as trituration. Mortars and pestles are used as drug paraphernalia to grind up pills to speed up absorption when they are ingested, or in preparation for insufflation. To finely ground drugs, not available in liquid dosage form is used if patients need artificial nutrition such as parenteral nutrition or by nasogastric tube. Mortars are used in cooking to prepare wet or oily ingredients such as guacamole and pesto, as well as grinding spices into powder.
The molcajete, a version used by pre-Hispanic Mesoamerican cultures including the Aztec and Maya, stretching back several thousand years, is made of basalt and is used in Mexican cooking. Other Native American nations use mortars carved into the bedrock to other nuts. Many such depressions can be found in their territories. In Japan large mortars are used with wooden mallets to prepare mochi. A regular sized Japanese mortar and pestle are called surikogi, respectively. Granite mortars and pestles are used in Southeast Asia, as well as India. In India, it is used extensively to make spice mixtures for various delicacies as well as day to day dishes. With the advent of motorized grinders, use of the mortar and pestle has decreased, it is traditional in various Hindu ceremonies to crush turmeric in these mortars. In Malay, it is known as batu lesung. Large stone mortars, with long wood pestles were used in West Asia to grind meat for a type of meatloaf, or kibbeh, as well as the hummus variety known as masabcha.
In Indonesia and the Netherlands mortar is known as Cobek or Tjobek and pestle is known as Ulekan or Oelekan. It is used to make fresh sambal, a spicy chili condiment, hence the sambal ulek/oelek denote its process using pestle, it is used to grind peanut and other ingredients to make peanut sauce for gado-gado. Large mortars and pestles are used in developing countries to husk and dehull grain; these are made of wood, operated by one or more persons. Good mortar and pestle-making materials must be hard enough to crush the substance rather than be worn away by it, they can not be too brittle either. The material should be cohesive, so that small bits of the mortar or pestle do not mix in with the ingredients. Smooth and non-porous materials are trap the substances being ground. In food preparation, a rough or absorbent material may cause the strong flavour of a past ingredient to be tasted in food prepared later; the food particles left in the mortar and on the pestle may support the growth of microorganisms.
When dealing with medications, the prepared drugs may interact or mix, contaminating the used ingredients. Rough ceramic mortar and pestle sets can be used to reduce substances to fine powders, but stain and are brittle. Porcelain mortars are sometimes conditioned for use by grinding some sand to give them a rougher surface which helps to reduce the particle size. Glass mortars and pestles are fragile, but suitable for use with liquids. However, they do not grind as finely as the ceramic type. Other materials used include stone marble or agate, bamboo, steel and basalt. Mortar and pestle sets made from the wood of old grape vines have proved reliable for grinding salt and pepper at the dinner table. Uncooked rice is sometimes ground in mortars to clean them; this process must be repeated until the rice comes out white. Some stones, such as molcajete, need to be seasoned first before use. Metal mortars are kept oiled. Since the results obtained with hand grinding are neither reproducible nor reliable, most laboratories work with automatic mortar grinders.
Grinding time and pressure of the mortar can be adjusted and fixed, saving time and labor. The first automatic Mortar Grinder was invented by F. Kurt