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Iridium rich clay from the K-T Boundry near Gubbio in Italy Collected in the crack between the rocks shown in the photos Cretaceous–Paleogene boundary Price per bottle : 18 USD - Int Priority Shipping 10 Glass bottle : 25 x 16 mm - Weight : 5 grams https://www.ebay.com/itm/162984664192?ViewItem=&item=162984664192&ssPageName=ADME:L:LCA:US:1123 The Alvarez hypothesis posits that the mass extinction of the dinosaurs and many other living things during the Cretaceous–Paleogene extinction event was caused by the impact of a large asteroid on the Earth. Prior to 2013, it was commonly cited as having happened about 65 million years ago, but a 2013 paper by Renne et al. gave an updated value of 66 million years. Evidence indicates that the asteroid fell in the Yucatán Peninsula, at Chicxulub, Mexico. The hypothesis is named after the father-and-son team of scientists Luis and Walter Alvarez, who first suggested it in 1980. In March 2010, an international panel of scientists endorsed the asteroid hypothesis, specifically the Chicxulub impact, as being the cause of the extinction. A team of 41 scientists reviewed 20 years of scientific literature and in so doing also ruled out other theories such as massive volcanism. They had determined that a 10–15 km (6–9 mi) space rock hurtled into earth at Chicxulub. For comparison, the Martian moon Phobos is 11 km (7 mi) and Mount Everest is just under 9 km (5.6 mi). The collision would have released the same energy as 100,000,000 megatonnes of TNT (4.2×1023 J), over a billion times the energy of the atomic bombs dropped on Hiroshima and Nagasaki. A 2016 drilling project into the peak ring of the crater strongly supported the hypothesis, and confirmed various matters that had been unclear until that point. These included the fact that the peak ring comprised granite (a rock found deep within the earth) rather than typical sea floor rock, which had been shocked, melted, and ejected to the surface in minutes, and evidence of colossal seawater movement directly afterwards from sand deposits. Crucially the cores also showed a near complete absence of gypsum, a sulfate-containing rock, which would have been vaporized and dispersed as an aerosol into the atmosphere, confirming the presence of a probable link between the impact and global longer-term effects on the climate and food chain. History Main article: Timeline of Cretaceous-Paleogene extinction event research In 1980, a team of researchers led by Nobel prize-winning physicist Luis Alvarez, his son, geologist Walter Alvarez, and chemists Frank Asaro and Helen Vaughn Michel discovered that sedimentary layers found all over the world at the Cretaceous–Paleogene boundary(K–Pg boundary; formerly called Cretaceous–Tertiary (K–T) boundary) contain a concentration of iridium hundreds of times greater than normal. Iridium is extremely rare in the Earth's crust because it is very dense and has the affinity for iron that characterizes the siderophile elements (see Goldschmidt classification), and therefore most of it sank into the Earth's core while the earth was still molten. The Alvarez team suggested that an asteroid struck the earth at the time of the Cretaceous–Paleogene boundary. In a 1953 publication, geologists Allan O. Kelly and Frank Dachille analyzed geological evidence from around the earth and concluded that one or more giant asteroids impacted the earth, causing an angular shift in the earth's axis, global floods, fire, atmospheric occlusion and causing extinction of the dinosaurs. There were other earlier speculations on the possibility of an impact event, but no evidence had been uncovered at that time Evidence The evidence for the Alvarez impact hypothesis is supported by chondritic meteorites and asteroids which contain a much higher iridium concentration than the Earth's crust. The isotopic ratio of iridium in meteorites is similar to that of the Cretaceous–Paleogene boundary layer but significantly different from the ratio in the Earth's crust. Chromium isotopic anomalies found in Cretaceous–Paleogene boundary sediments are similar to that of an asteroid or a comet composed of carbonaceous chondrites. Shocked quartz granules, glass spherules and tektites, indicative of an impact event, are common in the Cretaceous–Paleogene boundary, especially in deposits from around the Caribbean. All of these constituents are embedded in a layer of clay, which the Alvarez team interpreted as the debris spread all over the world by the impact. The location of the impact was unknown when the Alvarez team developed their hypothesis, but later scientists discovered the Chicxulub Crater in the Yucatán Peninsula, now considered the likely impact site.Using estimates of the total amount of iridium in the K–Pg layer, and assuming that the asteroid contained the normal percentage of iridium found in chondrites, the Alvarez team went on to calculate the size of the asteroid. The answer was about 10 kilometers (6 mi) in diameter, about the size of Manhattan. Such a large impact would have had approximately the energy of 1 x 108 megatons, i.e. about 2 million times as great as the most powerful thermonuclear bomb ever tested. Paul Renne of the Berkeley Geochronology Center has reported that the date of the asteroid event is 66,038,000 years ago, plus or minus 11,000 years, based on the radioactive decay of argon. He further posits that the mass extinction of dinosaurs occurred within 33,000 years of this date. Impact The most easily observable consequence of such an impact would be a vast dust cloud which would block sunlight and prevent photosynthesis for a few years, an event called an impact winter. This would account for the extinction of plants and phytoplankton and of all organisms dependent on them (including predatory animals as well as herbivores). But small creatures whose food chains were based on detritus would have a reasonable chance of survival. It is estimated that sulfuric acid aerosols were injected into the stratosphere, leading to a 10–20% reduction of solar transmission normal for that period. It would have taken at least ten years for those aerosols to dissipate. Global firestorms may have resulted as incendiary fragments from the blast fell back to Earth. Analyses of fluid inclusions in ancient amber suggest that the oxygen content of the atmosphere was very high (30–35%) during the late Cretaceous. This high O2 level would have supported intense combustion. The level of atmospheric O2 plummeted in the early Paleogene Period. If widespread fires occurred, they would have increased the CO2 content of the atmosphere and caused a temporary greenhouse effect once the dust cloud settled, and this would have exterminated the most vulnerable survivors of the "long winter". The impact may also have produced acid rain, depending on what type of rock the asteroid struck. However, recent research suggests this effect was relatively minor. Chemical buffers would have limited the changes, and the survival of animals vulnerable to acid rain effects (such as frogs) indicate this was not a major contributor to extinction. Impact hypotheses can only explain very rapid extinctions, since the dust clouds and possible sulphuric aerosols would wash out of the atmosphere in a fairly short time — possibly under ten years. Although further studies of the K–Pg layer consistently show the excess of iridium, the idea that the dinosaurs were exterminated by an asteroid remained a matter of controversy among geologists and paleontologists for more than a decade 2016 Chicxulub crater drilling project Main articles: Chicxulub crater and Cretaceous–Paleogene extinction event In 2016, a scientific drilling project drilled deep into the peak ring of the Chicxulub impact crater, to obtain rock core samples from the impact itself. The discoveries were widely seen as confirming current theories related to both the crater impact, and its effects. They confirmed that the rock comprising the peak ring had been subjected to immense pressures and forces and had been melted by immense heat and shocked by immense pressure from its usual state into its present form in just minutes; the fact that the peak ring was made of granite was also significant, since granite is not a rock found in sea-floor deposits, it originates much deeper in the earth and had been ejected to the surface by the immense pressures of impact; that gypsum, a sulfate-containing rock that is usually present in the shallow seabed of the region, had been almost entirely removed and must therefore have been almost entirely vaporized and entered the atmosphere, and that the event was immediately followed by a huge megatsunami (a massive movement of sea waters) sufficient to lay down the largest known layer of sand separated by grain size directly above the peak ring. These strongly support the hypothesis that the impactor was large enough to create a 120 mile peak ring, to melt, shock and eject basement granite from the midcrust deep within the earth, to create colossal water movements, and to eject an immense quantity of vaporized rock and sulfates into the atmosphere, where they would have persisted for a long time. This global dispersal of dust and sulfates would have led to a sudden and catastrophic effect on the climate worldwide, large temperature drops, and devastated the food chain
Bi-color natural gem Zoisite var Tanzanite - FOR SALE Merelani Hills , Lelatema Mts, Manyara Region, Tanzania Dimensions : 24 x 18 x 8 mm Price : 980 USD - Insured shipping : 30 USD Bi-color crystals are unusual and untreated. A significant percentage of tanzanite crystals on the market have been heat-treated (400-500°C) to produce or enhance its colour, many are originally brown or pale grey. A red tint seen looking down the c-axis is a indication that the crystal colouration is natural. It is noted for its remarkably strong trichroism, appearing sapphire blue, violet and burgundy depending on the position of crystal. Tanzanite also appears differently when viewed under alternate lighting conditions. In good quality the colour is ultramarine to sapphire blue; in artificial light, it appears more amethyst violet.
Rare fluorescent and phosphorescent specimen - Willemite and calcite - Excelsior Claim - Zambia - late 1950's Interesting 1st and 2nd generation growth of Willemite 1st picture in SW- UV 2rd picture after switching off UV lamp showing phosphorescence - 3rd in natural light Size : 65 x 56 x 46 mm Weight : 298 grams Price : 130 USD - Int Priority Shipping : 12
Rare Spessartine garnet in quartz. Diamantina, Minas Gerais, Brazil
Ocean Jasper - Set of 3 matching cabs for sale Total weight : 90.15 carat - Sizes : Large - 52.7 x 27.5 x 5.7mm - Small : 35.5 x 17.5 x 5 mm BIN Price : 98.00 - Int priority shipping 10
"Geologists are very pleasant companions, especially for geologists. It’s their art, to stop at every stone, and carry out an investigation at every layer of earth and that’s why I love this science so much. It is infinite and boundless as all poetry!" The Mukurob (Finger of God) near Asab in Namibia, was a sandstone rock formation in the Namib desert which collapsed on 7 December 1988. Mukurob consisted mostly of sandstone. The structure was 12 m high and up to 4.5 m wide, and weighed some 450 tons. What made Mukorob so special, however, was its base. Just 3 m long and 1.5 m wide, it was much narrower than the mass of rock which it supported. Mukurob was once part of the Weissrand Plateau before 50,000 years of erosion slowly isolated the structure from the rest of the plateau. It is still not known what truly caused Mukurob's collapse on the night of 7 December 1988. It is believed that a rainstorm, which occurred during the week before, may have weakened the sandstone pillar, and contributed to the structure's demise. Another study showed that the Spitak earthquake in Armenia registered heavily in Namibia on the night that Mukurob collapsed. The collapsed rock was discovered the next morning by a farmer and three sons.
Rare and very large Pezzottaite cabochon - 190.52 carats Size : 32.64 x 31.88 x 22.90 mm Most cut pezzottaite gems are under one carat (200 mg) in weight and rarely exceed two carats (400 mg). Sakavalana mine, Ambatovita, Mandrosonoro Commune, Ambatofinandrahana District, Amoron'i Mania Region, Fianarantsoa Province, Madagascar Related to beryl. Pezzottaite is trigonal while beryl is hexagonal. Named by Brendan M. Laurs, et al. in 2003 in honor of Federico Pezzotta (28 October 1965, Bergamo, Italy - ), petrologist and curator at the Museo Civico, Milano, Italy, for his work on Madagascar's granitic pegmatites. Pezzottaite, marketed under the name raspberyl or raspberry beryl, is a newly identified mineral species, first recognized by the International Mineralogical Association in September 2003. Pezzottaite is a caesium analogue of beryl, a silicate of caesium, beryllium, lithium and aluminium, with the chemical formula Cs(Be2Li)Al2Si6O18. Named after Italian geologist and mineralogist Federico Pezzotta, pezzottaite was first thought to be either red beryl or a new variety of beryl ("caesium beryl"); unlike actual beryl, however, pezzottaite contains lithium and crystallizes in the trigonal crystal system rather than the hexagonal system. Colors include shades of raspberry red to orange-red and pink. Recovered from miarolitic cavities in the granitic pegmatite fields of Fianarantsoa province, southern Madagascar, the pezzottaite crystals were small—no more than about 7 cm (2.8 in) in their widest dimension—and tabular or equant in habit, and few in number, most being heavily included with growth tubes and liquid feathers. Approximately 10 per cent of the rough material would also exhibit chatoyancy when polished. Most cut pezzottaite gems are under one carat (200 mg) in weight and rarely exceed two carats (400 mg). With the exception of hardness (8 on Mohs scale), the physical and optical properties of pezzottaite—i.e., specific gravity 3.10 (average), refractive index 1.601 to 1.620, birefringence 0.008 to 0.011 (uniaxial negative)—are all higher than typical beryl. Pezzottiate is brittle with a conchoidal to irregular fracture, and streaks white. Like beryl, it has an imperfect to fair basal cleavage. Pleochroism is moderate, from pink-orange or purplish pink to pinkish purple. Pezzottaite's absorption spectrum, as seen by a hand-held (direct vision) spectroscope, features a band at 485–500 nm with some specimens showing additional weak lines at 465 and 477 nm and a weak band at 550 to 580 nm. Most (if not all) of the Madagascan deposits have since been exhausted. Pezzottaite has been found in at least one other locality, Afghanistan: this material was first thought to be caesium-rich morganite (pink beryl). Like morganite and bixbite, pezzottaite is believed to owe its color to radiation-induced color centres involving trivalent manganese. Pezzottaite will lose its color if heated to 450 °C for two hours, but the color can be restored with gamma irradiation. This specimen is for sale and asking price is 3 million Euro !!
Amethyst Crystals Karoi , Mashonaland West , Zimbabwe Average size :30mm NW of the city of Harare there are small amethysts in pegmatite Beryl, feldspar mica composite. The crystals are often doubly terminated with acicular inclusions of goethite and hematite A scepter quartz is often defined as a quartz crystal that has a second generation crystal tip sitting on top of an older first generation crystal Scepters are quite common in certain geological environments. Amethyst from alpine-type fissures in igneous and highly metamorphosed rocks usually occurs as scepters on top of colorless or smoky crystals (not only in the Alps, but for example also in southern Norway or northern Greece). Here, the amethyst generation grew at lower temperatures than the first generation quartz. The same growth form can be observed in pegmatites and miaroles in igneous rocks (for example, amethyst scepters from the Brandberg, Namibia, or from pegmatites in Minas Gerais, Brazil). Scepters, or to be precise, the "second generation" part of a scepter quartz that defines it, commonly have a number of morphological properties: Scepters are commonly of normal habit and are never tapered. The underlying "first generation" crystal may show a Tessin habit, but the scepter on it will not. Scepters tend to assume a short prismatic habit. An apparent exception are reverse scepters and the normal scepters associated with them, which may occur as elongated extensions of a "first generation" crystal, but then in the shape of multiple stacked scepters. Many scepters show only a weak striation on their prism faces, sometimes it is even missing. Scepters do not show split growth patterns. Scepters rarely show trigonal habits with very small or missing z-faces. An exception are reverse scepters and the normal scepters associated with them. Scepters are often associated with skeleton growth forms (skeleton or window quartz). Scepters commonly show a color, color distribution, diapheny and surface pattern that is markedly different from the underlying "first generation" crystal. Often they are more colorful and transparent. Amethyst scepters are very common, smoky quartz scepters -often with uneven color distribution- are common. An exception are reverse scepters and the normal scepters associated with them which seem to either not differ from the "first generation" or show gradual transitions. Summarizing the exceptions above: Reverse scepters and the normal scepters associated with them seem to have a different set of properties. Formation One theory is that a scepter forms when crystal growth is interrupted and parts of the crystal are covered with some material that inhibits further growth. The growth inhibiting material might be only present as a very thin layer and invisible. The very tip of the crystal or the entire rhombohedral faces remain free of that material, and should the conditions change again, the crystal continues to grow from the tip. One of the problems with that theory is that you would expect to see a larger number of "double", "triple" or "quadruple scepters", specimen in which the growth had been interrupted several times and in which scepters with slowly changing habits are stacked. In nature, however, you see a strong dominance of "simple" scepters that consist of just a prism with "a single head". If you see multiple scepters, then often alongside simple scepters, although multiple changes in the environment should have affected the morphology of all of them equally. Another problem is that you would not expect to see a fully-grown scepter that encloses the former tip like an onion if the crystal simply started growing from a single point on the surface of the tip. Such a crystal would finally grow into an elongated crystal and would at best assume the shape of a reverse scepter. Specimens and photography - (C) Classic Rocks and Gems
Jasper-Agate Designer Cabochons from Sardinia for sale PM for weights, sizes, prices and availability Cutting and photography - (C) Classic Rocks and Gems This particular stone is known as Agate-Jasper - A variety of Agate consisting of Jasper veined with Chalcedony and is found only in a few localities worldwide - Sardinia in Italy, Rhineland- Palatinate, Germany - Catamarca , Argentina - Arizona, New Mexico, California N and S Dakota, Oregon and Utah in the USA - another possibility is also Iran according to the literature. The correct definition is chalcedonic quartz consisting of jasper and agate A rare beautiful stone when polished and can hold areas of complete transparency. Jasper is an opaque variety of chalcedony. Neither light nor images pass through. Agate is a translucent to semitransparent chalcedony. The Difference Between Agate and Jasper The primary difference between agate and jasper is in their diaphaneity. The word “diaphaneity” is used to describe “how easily light passes through a material.” There are three general levels of diaphaneity. They are, from highest to lowest: Transparent (light and images pass through) Translucent (light passes through) Opaque (no light passes through) ********** The magnitude of the quartz family is second only to feldspar in the composition of Earth’s crust. Agate and jasper are varieties of chalcedony that are made up of tiny crystals of quartz not visible to the unaided eye. These micro- and cryptocrystalline forms of quartz have fascinated both kings and the common man since antiquity. Agate was first mentioned in literature in a treatise “On Stones,” by Theophrastus (372-287 BCE). He referred to it as a beautiful stone that was highly valued. Later, according to Pliny the Elder in his “Natural History” (77 CE), agate was much more plentiful and varied and thus its value decreased. Both Pliny and Theophrastus wrote that agate derived its name from the river Achates in Sicily, where it was likely found for the first time. Agates and jaspers are formed in infinite varieties of multicolored patterns − each a unique creation of nature’s art. They are found in rich fall colors of orange, brown and golden hues and form in layers or bands of colors. They also form as “thunder eggs,” which are nodule-like or geode-like formations. Amorphous and swirling patterns − that can resemble galaxies or orbiting planets – are visible in some agates.