Banded Flint (aka Striped Flints)

Dietary minerals are the chemical elements required by living organisms, other than the four elements Carbon, Hydrogen, Nitrogen, and Oxygen which are ubiquitous in organic molecules. They can be either bulk minerals (required in relatively large amounts) or trace minerals (required only in very small amounts).

These can be naturally occurring in food or added in elemental or mineral form, such as calcium carbonate or sodium chloride. Some of these additives come from natural sources such as ground oyster shells. Sometimes minerals are added to the diet separately from food, as vitamin and mineral supplements and in dirt eating, called pica or geophagy.

Appropriate intake levels of each dietary mineral must be sustained to maintain physical health. Excessive intake of a dietary mineral may either lead to illness directly or indirectly because of the competitive nature between mineral levels in the body. For example, large doses of zinc are not really harmful unto themselves, but will lead to a harmful copper deficiency (unless compensated for, as in the Age-Related Eye Disease Study).

Soils in different geographic areas contain varying quantities of minerals.Contents
1 Bulk Minerals
2 Trace Minerals
3 Other Minerals
4 Food sources
5 See also
6 External links
7 References

Bulk Minerals

In Human nutrition, the dietary bulk mineral elements (RDA > 200 mg/day) are (in alphabetical order):
Calcium
Chlorine
Magnesium
Phosphorus
Potassium
Sodium
Sulfur

Trace Minerals

The most important trace mineral elements (RDA < 200 mg/day) are (again, in alphabetical order):
Chromium
Cobalt
Copper
Fluorine
Iodine
Iron
Manganese
Molybdenum
Selenium
Zinc

Iodine is required in larger quantities than the other trace minerals in this list and is sometimes counted with the bulk minerals. Sodium is not generally found in dietary supplements, despite being needed in large quantities, because the mineral is so common in food. This list is not an endorsement of the need of any of these minerals as dietary supplements.

Other Minerals

Many other minerals have been suggested as required in human nutrition, in varying quantities. Standards of evidence vary for different elements, and not all have been definitively established as essential to human nutrition. Common candidates include:

(elements for which convincing scientific evidence is lacking are marked as suspect)
Bismuth (suspect)
Boron
Nickel
Rubidium (suspect)
Silicon
Strontium (suspect)
Tellurium (suspect)
Titanium (suspect)
Tungsten (some organisms use tungsten rather than molybdenum)
Vanadium

Various other elements found in food supplies may vary from holding no known nutritional value (such as silver) to being toxic (such as mercury).

Food sources
Dairy products and green leafy vegetables for Calcium
Nuts, soy beans, and cocoa for Magnesium
Table salt (sodium chloride, the main source), milk and spinach for Sodium
Legumes, whole grains, and bananas for Potassium
Table salt is its main dietary source for Chlorine
Meat, eggs, and legumes for Sulfur
Red meat, leafy vegetables for iron

A large body of research suggests that humans often can benefit from mineral supplementation. Vitamins and minerals are interdependent, requiring the presence of one another for full benefit; taking a multivitamin without minerals is not nearly as effective as taking one with minerals. Extensive university research also demonstrates that the most bioavailable form of supplemental mineral is the chelated mineral (one that is bonded to a specific-size amino acid).

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Minerals are natural compounds formed through geological processes. The term “mineral” encompasses not only the material’s chemical composition but also the mineral structures. Minerals range in composition from pure elements and simple salts to very complex silicates with thousands of known forms (organic compounds are usually excluded). The study of minerals is called mineralogy.

Mineral definition and classification

To be classified as a “true” mineral, a substance must be a solid and have a crystal structure. It must also be an inorganic, naturally-occurring, homogenous substance with a defined chemical composition. The chemical composition may vary between end members of a mineral system. For example the plagioclase feldspars comprise a continuous series from sodium-rich albite (NaAlSi3O8) to calcium-rich anorthite (CaAl2Si2O8) with four recognized intermediate compositions between. Mineral-like substances that don’t strictly meet the definition are sometimes classified as mineraloids. Other natural-occurring substances are Nonminerals.

A crystal structure is the orderly geometric spatial arrangement of atoms in the internal structure of a mineral. There are 14 basic lattice arrangements of atoms in three dimensions in the six crystal systems, and all crystal structures currently recognized fit in one of these 14 arrangements. This crystal structure is based on regular internal atomic or ionic arrangement that is often visible as the mineral form. Even when the mineral grains are too small to see or are irregularly shaped the crystal structure can be determined by x-ray analysis and/or optical microscopy.

Chemistry and crystal structure define together a mineral. In fact, two or more minerals may have the same chemical composition, but differ in crystal structure (these are known as polymorphs). For example, pyrite and marcasite are both iron sulfide. Similarly, some minerals have different chemical compositions, but the same crystal structure: for example, halite (made from sodium and chlorine), galena (made from lead and sulfur) and periclase (made from magnesium and oxygen) all share the same cubic crystal structure.

Crystal structure greatly influences a mineral’s physical properties. For example, though diamond and graphite have the same composition (both are pure carbon), graphite is very soft, while diamond is the hardest of all known minerals.

There are currently just over 4,000 known minerals, according to the International Mineralogical Association, which is responsible for the approval of and naming of new mineral species found in nature.

Minerals and rocks

A mineral is a naturally occurring, inorganic substance with a definite chemical composition and a crystalline structure. A rock is an aggregate of two or more minerals. (A rock may also include organic remains.) The specific minerals in a rock can vary a lot. Some minerals, like quartz, mica or feldspar are common, while others have been found in only one or two locations worldwide. Over half of the mineral species known are so rare that they have only been found in a handful of samples, and many are known from only one or two small grains.

Physical properties of minerals

Classifying minerals can range from simple to very difficult. A mineral can be identified by several physical properties, some of them being sufficient for full identification without equivocation. In other cases, minerals can only be classified by more complex chemical or X-ray diffraction analysis; these methods, however, can be costly, time-consuming, and even risk damaging the sample.

Physical properties commonly used are :
Crystal structure and habit: See the above discussion of crystal structure. A mineral may show good crystal habit or form, or it may be massive, granular or compact with only microscopically visible crystals.
Hardness: the physical hardness of a mineral is usually measured according to the Mohs scale of mineral hardness.
Luster indicates the way a mineral’s surface interacts with light and can range from dull to glassy (vitreous).
Color indicates the appearance of the mineral in reflected light or transmitted light for translucent minerals (i.e. what it looks like to the naked eye).
Streak refers to the color of the powder a mineral leaves after rubbing it on an unglazed porcelain streak plate.
Cleavage describes the way a mineral may come apart or cleave in different ways. In thin section, cleavage is visible as thin parallel lines across a mineral.
Fracture describes how a mineral breaks when broken contrary to its natural cleavage planes.
Specific gravity relates the mineral mass to the mass of an equal volume of water, namely the density of the material.
Other properties: fluorescence (response to ultraviolet light), magnetism, radioactivity, tenacity (response to mechanical induced changes of shape or form), and reactivity to dilute acids.

Chemical properties of minerals

Minerals may be classified according to chemical composition. They are here categorized by anion group. The list below is in approximate order of their abundance in the Earth’s crust. The list follows the Dana classification system.

Silicate class

The largest group of minerals by far are the silicates, which are composed largely of silicon and oxygen, with the addition of ions such as aluminium, magnesium, iron, and calcium. Some important rock-forming silicates include the feldspars, quartz, olivines, pyroxenes, amphiboles, garnets, and micas.

Carbonate class

The carbonates consist of those minerals containing the anion (CO3)2- and include calcite and aragonite (both calcium carbonate), dolomite (magnesium/calcium carbonate) and siderite (iron carbonate). Carbonates are commonly deposited in marine settings when the shells of dead planktonic life settle and accumulate on the sea floor. Carbonates are also found in evaporitic settings (e.g. the Great Salt Lake, Utah) and also in karst regions, where the dissolution and reprecipitation of carbonates leads to the formation of caves, stalactites and stalagmites. The carbonate class also includes the nitrate and borate minerals.

Sulfate class

Sulfates all contain the sulfate anion, in the form SO42-. Sulfates commonly form in evaporitic settings where highly saline waters slowly evaporate, allowing the formation of both sulfates and halides at the water-sediment interface. Sulfates also occur in hydrothermal vein systems as gangue minerals along with sulfide ore minerals. Another occurrence is as secondary oxidation products of original sulfide minerals. Common sulfates include anhydrite (calcium sulfate), celestite (strontium sulfate), barite (barium sulfate), and gypsum (hydrated calcium sulfate). The sulfate class also includes the chromate, molybdate, selenate, sulfite, tellurate, and tungstate minerals.

Halide class

The halides are the group of minerals forming the natural salts and include fluorite (calcium fluoride), halite (sodium chloride), sylvite (potassium chloride), and sal ammoniac (ammonium chloride). Halides, like sulfates, are commonly found in evaporitic settings such as playa lakes and landlocked seas such as the Dead Sea and Great Salt Lake. The halide class includes the fluoride, chloride, and iodide minerals.

Oxide class

Oxides are extremely important in mining as they form many of the ores from which valuable metals can be extracted. They commonly occur as precipitates close to the Earth’s surface, oxidation products of other minerals in the near surface weathering zone, and as accessory minerals in igneous rocks of the crust and mantle. Common oxides include hematite (iron oxide), magnetite (iron oxide), chromite (chromium oxide), spinel (magnesium aluminium oxide - a common component of the mantle), rutile (titanium dioxide), and ice (hydrogen oxide). The oxide class includes the oxide and the hydroxide minerals.

Sulfide class

Many sulfides are economically important as metal ores. Common sulfides include pyrite (iron sulfide - commonly known as fools’ gold), chalcopyrite (copper iron sulfide) and galena (lead sulfide). The sulfide class also includes the selenides, the tellurides, the arsenides, the antimonides, the bismuthinides, and the sulfosalts (sulfur and a second anion such as arsenic).

Phosphate class

The phosphate group actually includes any mineral with a tetrahedral unit AO4 where A can be phosphorus, antimony, arsenic or vanadium. By far the most common phosphate is apatite which is an important biological mineral found in teeth and bones of many animals. The phosphate class includes the phosphate, arsenate, vanadate, and antimonate minerals.

Element class

The Elemental group includes metals and intermetallic elements (gold, silver, copper), semi-metals and non-metals (antimony, bismuth, graphite, sulfur). This group also includes natural alloys, such as electrum (a natural alloy of gold and silver), phosphides, silicides, nitrides and carbides (which are usually only found naturally in a few rare meteorites).

Dietary mineral

Dietary minerals are inorganic compounds necessary for life and good nutrition. Some of these are scientific minerals such as salt; others are elements, such as potassium, calcium, iron, zinc, magnesium, copper. These can be naturally occurring in food or added in elemental or mineral form, such as calcium carbonate or sodium chloride. Some of these additives come from natural sources such as ground oyster shells. Sometimes minerals are added to the diet separately from food, as vitamin and mineral supplements and in dirt eating, called pica or geophagy.

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Gemstones are the prettier, more expensive stones which are usually faceted and mounted into different types of jewelry or displayed on a piece of cotton or felt.

The main gemstones are: diamond, ruby, sapphire, emerald, topaz, amethyst, agate, tiger’s eye, jade, lapis lazuli, opal and turquoise. Of all these stones, the agate is just about the only one found in Missouri though several of the others are found in other places in the United States, such as, diamonds, rubies, sapphires, emeralds, topaz quartz, amethyst, opals, and turquoise.

Diamonds are the hardest and most precious of all stones with a hardness point of 10, the highest on the scale. The colors of diamonds range from colorless to yellow, brown, light red, blue, green and violet. Africa produces more than one-half of the world’s diamonds.

The ruby, from the Corundum group, has a hardness point of 9 and is a red color. Rubies and sapphires are the same stone except for color. The sapphire has several colors such as blue, purple, yellow, orange, green and colorless. A blue ruby is a sapphire and a red sapphire is really a ruby.

The different kinds of Missouri gemstones including flint, jasper and Drusey quartz.

Geodes are hollow while the thunder eggs have solid centers.

This close-up of Lake Superior agate shows the tiny lines in the stone.

The emerald from the Beryl group has a hardness point of 7.5 to 8 and is an intense green color. The emerald is one of the three semi-precious stones.

Topaz has a hardness point of 8 and is brown, yellow, blue, light red or colorless, while topaz quartz or citrine is a very pretty yellow to brown stone with a hardness of 7.

Amethyst is also a form of quartz with a hardness point of 7. Amethyst is found on Mt. Antero in Colorado, a 14,000 foot peak, second highest peak in the world where gemstones are found.

The agate, a type of quartz with a hardness point of 7, comes in various colors. The one that might be found in Missouri is the Lake Superior agate which is washed down onto the gravel bars on the Mississippi River from Lake Superior.

Tiger’s eye, a type or quartz with a hardness of 7, is brown with a silky luster or is sometimes dyed other colors.

There are two groups of jade jadeite and nephrite. The jadeite is in the 6.5 hardness group and the nephrite is from 6 to 6.5. The jadeite is green, yellow, white, violet and brown, while the nephrite has all the above colors plus gray and black. In the United States jade is found mostly in Florida.

Lapis lazuli of the lazurite group has a hardness of 6 to 6.5 with an intense dark blue with flecks of yellow pyrite color to it. Lapis lazuli is a pretty stone from Afghanistan that was first brought to Europe by Marco Polo.

Another very pretty rock, the opal is softer than a lot of the other rocks with a 5 to 6.5 hardness point. Opals range from white or dark gray to black background with vivid flashes of color in patches. The black opal is from Australia and Mexico and looks almost green rather than black. In the United States Nevada is first in production and Idaho and Arizona are probably next. Most opals have a matrix around them which is as hard as the rock itself. The matrix looks like clay that has hardened around the opal and is sometimes left around the stone to prove it is genuine.

Turquoise is a light blue stone, with a hardness point of 5 to 6. Turquoise was used by the American Indians of the Southwest to make jewelry. There continues to be a profitable market for turquoise jewelry.

Perhaps the most important of all precious minerals is gold. Perhaps no other element has had as much influence historically than the search for and acquisition of gold.. Nor has its importance decreased. On the contrary its value today is greater than ever before. Because of its value, everyone would like to find gold, and panning for gold is still a profitable venture if there is enough gold to pan. Mr. Ezard explained how to pan for gold using some gold ore he brought back from Canada.

First you need a gold pan which has baffles in it–little ridges along one side of the pan. Then put some of the ore in the pan and add enough water to wash the ore around in the pan. Swish the ore around, slowly washing out the pebbles and dirt. The baffles will help keep most of the gold from falling out of the pan but not all of it. Just keep washing out the dirt ore until you can’t get much more out without losing all of the gold.

To separate the gold from the remaining impurities, use mercury because mercury has a specific gravity, or weight per cubic measure, so that everything but gold will float. The gold will be absorbed. Then after pouring off the particles that are floating, all that is left is the gold and mercury. The next step is to evaporate the mercury. But since evaporated mercury lets off a deadly gas, it must be done safely. There is a homemade way to do it. Hollow out a cavity in an average potato, pour the mercury and gold mixture in, put the other half of the potato on, and tie it together very tightly with wire. Then heat it in an oven that is well ventilated. Be sure to get away to not breathe any of the fumes, After a time the mercury will evaporate, leaving the gold.

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Striped flint, a unique stone as hard as a diamond, cannot be found anywhere except in the Sandomierz region. Jewellery with this stone was put on display at the Regional Museum in Toruń in mid-February.

“For years, striped flint was regarded as a ‘weed’ obstructing the extraction of lime. Now, jewelers in Germany and Austria are vying with each other to get hold of it”, says the exhibition’s curator, Katarzyna Kluczwejd. The exhibition is entitled: “Structures, textures, forms of Cezary Łutowicz in striped flint”.

The unique properties of striped flint have been used by Cezary Łutowicz, a Sandomierz goldsmith, for thirty years. He was the first in the world to start producing jewellery with it, and it has now found its way into many Polish museums as well as the Vatican collection.

Apart from Łutowicz’s jewellery, the Toruń exhibition presents natural compositions of this stone, whose shapes arouse connotations with works of art from Paleolithic figures of Venus up to contemporary sculpture.

Striped flint is also called the “stone of optimising”, which refers to the magic meanings which were once upon a time ascribed to the jeweler’s stones and gems. Broken, it shows circles of white, black, gray, beige and brown.

As to its origins, the most popular theory is that it was formed 150 million years ago, as a result of a colony of sea sponges dying out. Striped flint only occurs in Poland in the vicinity of Ożarów, Iłża and Krzemianki in the Sandomierz region.

The exhibition will be on display at the Kamienica pod Gwiazdą in Toruń’s Old Town Market until the end of March.

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Recently i found “Striped Flint - the Polish diamond” thread on Bead Style Magazine Forum. Lovesome writes:

The focal stone in this necklace is a stone that can only be found in Poland. It is very popular now, since there’s not too much of it left in the mines and it is almost as hard as diamonds. It was combined with three various kinds of jasper and oxidised silver.

Banded fling jewelry above

Check it at Bead Style Magazine!

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Obsidian is a type of naturally occurring glass, produced by volcanoes (igneous origin) when a felsic lava cools rapidly and freezes without sufficient time for crystal growth (see glass transition temperature). It is commonly found within the margins of felsic lava flows, where cooling is more rapid. Because of the lack of crystal structure, obsidian blade edges can reach almost molecular thinness, leading to its ancient use as arrowheads, and its modern use as surgical scalpel blades.

While a rock like basalt is dark because of ferromagnesian enrichment, obsidian consists mainly of SiO2 (silicon dioxide), 70% or more. Obsidian is mineral-like, but not a true mineral because it is not crystalline.

Obsidian was highly valued in certain Stone Age cultures because, like flint, it can be fractured to produce sharp blades or arrowheads. Like all glass and some other types of naturally occurring rocks, obsidian breaks with a characteristic conchoidal fracture. It may also have been polished to create early mirrors.

Obsidian is used in cardiac surgery, as well-crafted obsidian blades have a cutting edge up to five times sharper than high-quality steel surgical scalpels, with the edge of the blade reaching veritable molecular thinness. It produces a cleaner cut and less tissue trauma, which translates to faster healing and less scar tissue

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Ferrocerium is the “flint” in lighters, and its ability to give a much larger number of sparks when scraped against a rough surface (pyrophoricity) is used in many other applications, such as clockwork toys and strikers for welding torches. Also known as Auermetall after its inventor Baron Carl Auer von Welsbach, it is sold under such trade names as Blastmatch, Fire Steel, and Metal-Match.

While ferrocerium-and-steel function in a similar way to flint-and-steel in fire starting, ferrocerium actually takes on the role that steel played in traditional methods. When small shavings of it are removed quickly enough, the heat generated by friction is enough to ignite those shavings. The sparks generated are in fact tiny pieces of burning metal.

Lighter “flint” is composed mostly of an alloy of rare earth metals called mischmetal, mischmetal containing approximately 50% cerium and 45% lanthanum, with small amounts of neodymium and praseodymium. The origin of its easy sparking is cerium’s low temperature pyrophoricity, its ignition temperature occurring between (150 to 180 degrees celsius). Since smaller scrapings become better sparks, the mechanical properties of rare earth metals must be adjusted to give a usable material; to that end, at least two strategies have been developed to make such alloys more brittle:
Oxide - most contemporary flints are hardened with 20% iron oxide and 2% magnesium oxide.
Intermetallic - in the Baron von Welsbach’s original alloy, 30% iron (ferrum) was added to purified cerium, hence the name “ferro-cerium”. Iron reacts with rare earth metals to form hard intermetallic compounds similar to those in neodymium magnets; such magnets are also known to generate sparks quite easily when broken.

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Chalcedony is one of the cryptocrystalline varieties of the mineral quartz, having a waxy luster. Chalcedony may be semitransparent or translucent and is usually white to gray, grayish-blue or some shade of brown, sometimes nearly black. Other shades have been given different names. A clear red chalcedony is known as carnelian or sard; a green variety colored by nickel oxide is called chrysoprase. Prase is a dull green and onyx is black and white banded. Plasma is a bright to emerald-green chalcedony that is sometimes found with small spots of jasper resembling blood drops; it has been referred to as blood stone or heliotrope. Flint is also a variety of chalcedony.

People living along the Central Asian trade routes used various forms of chalcedony, including carnelian, to carve intaglios, ring bezels (the upper faceted portion of a gem projecting from the ring setting), and beads that show strong Graeco-Roman influence. Fine examples of first century objects made from chalcedony, possibly Kushan, were found in recent years at Tillya-tepe in north-western Afghanistan. Hot wax would not stick to it so it was often used to make seal impressions.

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In Europe, some of the best toolmaking flint has come from Belgium (Obourg, flint mines of Spiennes), the coastal chalks of the English Channel, the Paris Basin, the Sennonian deposits of Rügen, Grimes Graves in England and the Jurassic deposits of the Kraków-area in Poland. Flint mining is attested since the Palaeolithic, but became more common since the Neolithic (Michelsberg culture, Funnelbeaker culture).

Flint was one of the most commonly used materials for the manufacture of stone tools during the Stone Age, as it splits into thin, sharp splinters called flakes or blades (depending in the shape) when struck by another hard object (such as a hammerstone made of another material). This process is referred to as knapping.

When struck against steel, flint will produce sparks, which when directed onto tinder, can be used to start a fire. This occurs when the hard flint knocks off a particle of the steel, which is heated by the impact, and then burns with oxygen from the atmosphere. This method is popular in woodcraft and among campers who want to have an ‘authentic’ experience. Striking a lump of flint against a piece of steel to make fire is not particularly easy or convenient (although it is much easier than other primitive fire-making methods such as using a bow and drill). Because of this, a similar technology has been miniaturized and integrated into lighters, which are easy to use without skill or practice.
Starting a fire with flint is a staple of scouting lore.

A later major use was to create the spark that would ignite the powder that would fire a ball or bullet from a flintlock firearm. While the military use of a flintlock declined after the British military generally applied the percussion cap on their muskets in 1842, it is still popular to use the flintlock as a hunting rifle during special muzzleloader seasons or general rifle seasons in several states in the US.

Flint was used extensively from the 13th century until the present day as a material for building stone walls, especially in parts of England. In chalky coastal areas of England flint has also been used as a building and walling material, predating the common use of bricks but laid in a similar manner, using lime mortar. For instance, flint was used in the construction of many churches and other buildings in East Anglia.

Flint pebbles are used as the media in ball mills to grind glazes and other raw materials for the ceramics industry. The pebbles are hand-selected for colour, with those showing a reddish tint, indicating the presence of iron, being discarded. The remaining blue-grey stones have a low content of chromophoric oxides and so should impart lesser amounts of colouring contaminants.

In England flint pebbles were traditionally an important raw material for clay based ceramic bodies; after high temperature treatment, to remove organic impurites and induce certain physical reactions, calcined flint performed a similar role to quartz sand used in other countries, i.e. after milling to fine particle size was the filler component in pottery bodies. Because of this historical use American potters now, erroneously, refer to all siliceous fillers as flint.

source: wikipedia

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Flint (or flintstone) is a hard, sedimentary cryptocrystalline silicate form of the mineral quartz, categorized as a variety of chalcedony. Flint is usually dark-grey, blue, black, or deep brown in colour, and often has a glassy appearance. It occurs chiefly as nodules and masses in sedimentary rocks, such as chalks and limestones.

The exact mode of formation of flint is not yet clear or agreed but it is thought that it occurs as a result of chemical changes in compressed sedimentary rock formations, during the process of diagenesis. One theory is that a gelatinous material fills cavities in the sediment, such as holes bored by crustaceans or molluscs and that this becomes silicified. This could certainly explain the complex shapes of flint that are found.

source: wikipedia.org

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