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Agate Belt
Agate ( ) is a banded variety of chalcedony. Agate stones are characterized by alternating bands of different colored chalcedony and sometimes include macroscopic quartz. They are common in nature and can be found globally in a large number of different varieties. There are some varieties of chalcedony without bands that are commonly called agate (moss agate, fire agate, etc.); however, these are more properly classified solely as varieties of chalcedony. Agates are primarily formed as nodules within volcanic rock, but they can also form in veins or in sedimentary rock. Agate has been popular as a gemstone in jewelry for thousands of years, and today it is also popular as a collector's stone. Some duller agates sold commercially are artificially dyed to enhance their color. Etymology Agate was given its name by Theophrastus, a Greek philosopher and naturalist. He discovered the stone c. 350 BCE along the shoreline of the River Achates (), now the Dirillo River, on the Italian i ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Tectosilicate
Silicate minerals are rock-forming minerals made up of silicate groups. They are the largest and most important class of minerals and make up approximately 90 percent of Earth's crust. In mineralogy, the crystalline forms of silica (silicon dioxide, ) are usually considered to be tectosilicates, and they are classified as such in the Dana system (75.1). However, the Nickel-Strunz system classifies them as oxide minerals (4.DA). Silica is found in nature as the mineral quartz, and its polymorphs. On Earth, a wide variety of silicate minerals occur in an even wider range of combinations as a result of the processes that have been forming and re-working the crust for billions of years. These processes include partial melting, crystallization, fractionation, metamorphism, weathering, and diagenesis. Living organisms also contribute to this geologic cycle. For example, a type of plankton known as diatoms construct their exoskeletons ("frustules") from silica extracted from sea ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Sedimentary Rock
Sedimentary rocks are types of rock (geology), rock formed by the cementation (geology), cementation of sediments—i.e. particles made of minerals (geological detritus) or organic matter (biological detritus)—that have been accumulated or deposited at Earth's surface. Sedimentation is any process that causes these particles to settle in place. Geological detritus originates from weathering and erosion of existing rocks, or from the solidification of molten lava blobs erupted by volcanoes. The geological detritus is transported to the place of deposition by water, wind, ice or Mass wasting, mass movement, which are called agents of denudation. Biological detritus is formed by bodies and parts (mainly shells) of dead aquatic organisms, as well as their fecal mass, suspended in water and slowly piling up on the floor of water bodies (marine snow). Sedimentation may also occur when dissolved minerals precipitate from aqueous solution, water solution. The sedimentary rock cover of ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Andesite
Andesite () is a volcanic rock of intermediate composition. In a general sense, it is the intermediate type between silica-poor basalt and silica-rich rhyolite. It is fine-grained (aphanitic) to porphyritic in texture, and is composed predominantly of sodium-rich plagioclase plus pyroxene or hornblende. Andesite is the extrusive equivalent of plutonic diorite. Characteristic of subduction zones, andesite represents the dominant rock type in island arcs. The average composition of the continental crust is andesitic. Along with basalts, andesites are a component of the Geology of Mars, Martian crust. The name ''andesite'' is derived from the Andes mountain range, where this rock type is found in abundance. It was first applied by Christian Leopold von Buch in 1826. Description Andesite is an aphanitic (fine-grained) to porphyritic (coarse-grained) igneous rock that is intermediate in its content of silica and low in alkali metals. It has less than 20% quartz and 10% feldspa ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Basalt
Basalt (; ) is an aphanite, aphanitic (fine-grained) extrusive igneous rock formed from the rapid cooling of low-viscosity lava rich in magnesium and iron (mafic lava) exposed at or very near the planetary surface, surface of a terrestrial planet, rocky planet or natural satellite, moon. More than 90% of all volcanic rock on Earth is basalt. Rapid-cooling, fine-grained basalt is chemically equivalent to slow-cooling, coarse-grained gabbro. The eruption of basalt lava is observed by geologists at about 20 volcanoes per year. Basalt is also an important rock type on other planetary bodies in the Solar System. For example, the bulk of the plains of volcanism on Venus, Venus, which cover ~80% of the surface, are basaltic; the lunar mare, lunar maria are plains of flood-basaltic lava flows; and basalt is a common rock on the surface of Mars. Molten basalt lava has a low viscosity due to its relatively low silica content (between 45% and 52%), resulting in rapidly moving lava flo ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Nodule (geology)
In geology and particularly in sedimentology, a nodule is a small, irregularly rounded knot, mass, or lump of a mineral or mineral aggregate that typically has a contrasting composition from the enclosing sediment or sedimentary rock. Examples include pyrite nodules in coal, a chert nodule in limestone, or a phosphorite nodule in marine shale. Normally, a nodule has a warty or knobby surface and exists as a discrete mass within the host strata. In general, they lack any internal structure except for the preserved remnants of original bedding or fossils. Nodules are closely related to '' concretions'' and sometimes these terms are used interchangeably. Minerals that typically form nodules include calcite, chert, apatite (phosphorite), anhydrite, and pyrite.Neuendorf, KKE, JP Mehl, Jr., and JA Jackson, eds. (2005) ''Glossary of Geology'' (5th ed.). Alexandria, Virginia, American Geological Institute. 779 pp. Boggs S, Jr. (2009) ''Petrology of Sedimentary Rocks.'' Cambridge Univ ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Sicily
Sicily (Italian language, Italian and ), officially the Sicilian Region (), is an island in the central Mediterranean Sea, south of the Italian Peninsula in continental Europe and is one of the 20 regions of Italy, regions of Italy. With 4.7 million inhabitants, including 1.2 million in and around the capital city of Palermo, it is both the largest and most populous island in the Mediterranean Sea. Sicily is named after the Sicels, who inhabited the eastern part of the island during the Iron Age. Sicily has a rich and unique culture in #Art and architecture, arts, Music of Sicily, music, #Literature, literature, Sicilian cuisine, cuisine, and Sicilian Baroque, architecture. Its most prominent landmark is Mount Etna, the tallest active volcano in Europe, and one of the most active in the world, currently high. The island has a typical Mediterranean climate. It is separated from Calabria by the Strait of Messina. It is one of the five Regions of Italy#Autonomous regions with s ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Italy
Italy, officially the Italian Republic, is a country in Southern Europe, Southern and Western Europe, Western Europe. It consists of Italian Peninsula, a peninsula that extends into the Mediterranean Sea, with the Alps on its northern land border, as well as List of islands of Italy, nearly 800 islands, notably Sicily and Sardinia. Italy shares land borders with France to the west; Switzerland and Austria to the north; Slovenia to the east; and the two enclaves of Vatican City and San Marino. It is the List of European countries by area, tenth-largest country in Europe by area, covering , and the third-most populous member state of the European Union, with nearly 59 million inhabitants. Italy's capital and List of cities in Italy, largest city is Rome; other major cities include Milan, Naples, Turin, Palermo, Bologna, Florence, Genoa, and Venice. The history of Italy goes back to numerous List of ancient peoples of Italy, Italic peoples—notably including the ancient Romans, ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Dirillo
The Dirillo, or Acate, is a river in Sicily which springs from the Hyblaean Mountains and flows through the areas of Vizzini, Licodia Eubea, Mazzarrone, Chiaramonte Gulfi, Acate, Vittoria, Gela. It enters the Strait of Sicily south-east of the town of Gela. As the largest river in the area it is sometimes known as the ''Fiume Grande''. The river was known in antiquity as the Achates (). It was noted by Silius Italicus for the remarkable clearness of its waters. Theophrastus in his treatise '' On Stones'' (ca. 315 B.C.) indicates that the name of the gemstone ''achates'' (agate) was based on the source of such stones from this river. Pliny the Elder makes the same connection in his ''Naturalis Historia'' at the [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Naturalist
Natural history is a domain of inquiry involving organisms, including animals, fungi, and plants, in their natural environment, leaning more towards observational than experimental methods of study. A person who studies natural history is called a naturalist or natural historian. Natural history encompasses scientific research but is not limited to it. It involves the systematic study of any category of natural objects or organisms, so while it dates from studies in the ancient Greco-Roman world and the mediaeval Arabic world, through to European Renaissance naturalists working in near isolation, today's natural history is a cross-discipline umbrella of many specialty sciences; e.g., geobiology has a strong multidisciplinary nature. Definitions Before 1900 The meaning of the English term "natural history" (a calque of the Latin ''historia naturalis'') has narrowed progressively with time, while, by contrast, the meaning of the related term "nature" has widened (see also ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Philosopher
Philosophy ('love of wisdom' in Ancient Greek) is a systematic study of general and fundamental questions concerning topics like existence, reason, knowledge, Value (ethics and social sciences), value, mind, and language. It is a rational and critical inquiry that reflects on its methods and assumptions. Historically, many of the individual sciences, such as physics and psychology, formed part of philosophy. However, they are considered separate academic disciplines in the modern sense of the term. Influential traditions in the history of philosophy include Western philosophy, Western, Islamic philosophy, Arabic–Persian, Indian philosophy, Indian, and Chinese philosophy. Western philosophy originated in Ancient Greece and covers a wide area of philosophical subfields. A central topic in Arabic–Persian philosophy is the relation between reason and revelation. Indian philosophy combines the Spirituality, spiritual problem of how to reach Enlightenment in Buddhism, enlighten ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Greeks
Greeks or Hellenes (; , ) are an ethnic group and nation native to Greece, Greek Cypriots, Cyprus, Greeks in Albania, southern Albania, Greeks in Turkey#History, Anatolia, parts of Greeks in Italy, Italy and Egyptian Greeks, Egypt, and to a lesser extent, other countries surrounding the Eastern Mediterranean and Black Sea. They also form a significant Greek diaspora, diaspora (), with many Greek communities established around the world.. Greek colonies and communities have been historically established on the shores of the Mediterranean Sea and Black Sea, but the Greek people themselves have always been centered on the Aegean Sea, Aegean and Ionian Sea, Ionian seas, where the Greek language has been spoken since the Bronze Age.. Until the early 20th century, Greeks were distributed between the Greek peninsula, the western coast of Asia Minor, the Black Sea coast, Cappadocia in central Anatolia, Egypt, the Balkans, Cyprus, and Constantinople. Many of these regions coincided to ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
