Contributions to Mineralization Online Course https://giladjames.com Section: Petrology, Geochemistry and Mineralogy of Greisens Associated with Tin-Tungsten Mineralisation: Hub Stock Deposit at Krásno–Horní Slavkov Ore District, Czech Republic Lesson: Introduction Contributions to Mineralization. This course is brought to you by Gilad James Mystery School. Learn more at Gilad James.com. Introduction Greisenisation is one of the most significant wall rock alterations, which occurs in granite-related tin-tungsten ore deposits. Historically, the term “greisen” has been used firstly by miners from the Krušné Hory/Erzgebirge Mts. to describe wall rocks consisting of quartz, mica and topaz surrounding the Sn-W mineralisation. This area hosts a number of Sn-W deposits (e.g., Cínovec/Zinnwald, Altenberg, Ehrenfriedersdorf, Krásno–Horní Slavkov) bound to greisenised stocks of the Variscan granitic bodies. These granites represent highly fractionated granites of the Krušné Hory/Erzgebirge batholith. Besides the Cornwall ore fields in England, these deposits were an important European source of tin from the Bronze Age until 1991. The largest Sn-W-Li-Nb-Ta ore deposit in the Krásno–Horní Slavkov ore district is part of the Hub and Schnöd granite stocks, where Sn-W mineralisation of the greisen type was exploited from the 1200s to 1991. The total historical production of the Krásno–Horní Slavkov ore district is estimated at 52,000 tons of tin . This study was carried out to characterise petrological, mineralogical and geochemical features of the Hub stock greisens. The presented data provide a basis for definition of the alteration zoning and also basis for estimating the magnitude of mass transfer and the integrated fluid flux involved in the formation of the stock greisen system. Geological setting The Krásno–Horní Slavkov ore district comprises mineralised topaz granite stocks along the SE margin of the Krudum granite body in the Slavkovský les Mts. area ( Figure 1 ). The Krudum granite body is part of the Western Erzgebirge pluton. The inner structure of the granite stocks in the Krásno–Horní Slavkov ore district is remarkably stratified, comprising greisens, weakly greisenised topaz alkali-feldspar granites, and layers of alkali-feldspar syenites ( Figure 2 ). According to the most widely accepted genetic models, the topaz alkali-feldspar granite stocks represent the apical parts of highly fractionated granite bodies. Greisens with Sn-W mineralisation are developed predominantly in the upper part of the Hub stock ( Figures 2 and 3 ). The greisens are represented according to modal classification predominantly by Li-mica-topaz and topaz-Li-mica greisens. The Li-mica and quartz greisens are less abundant. Very rare topaz greisens occur as small lenses in topaz-Li-mica greisens. Greisens occur in two structural types. The first and dominant one (greisens I) forms irregular bodies and lenses of various sizes. The uppermost part of the Hub stock is filled by massive greisen body, alternating deeper in the stock centres with weakly or intensively altered topaz granites. The lenticular greisen bodies are locally oriented parallel to the elongation of the stock; however, their form is usually irregular without sharp contact with weakly altered granites ( Figure 3 ). The second type (greisen II) forms fracture-controlled bodies, sometimes occurring together with quartz veins ( Figure 4a ). Geological sketch map of the Krásno–Horní Slavkov ore district. Schematic cross section of the south-eastern part of the Krudum granite body (after , modified by author). Schematic cross section of the hub stock (after , modified by author). (a) Greisenisation II developed around the fissure in weakly greisenised topaz granite, hub stock, 4 level; (b) cassiterite-rich ore domain hosted in weakly greisenised topaz granite, hub stock, 4 level (photo of M. Košatka, 1987). The occurrence of Sn-W mineralisation is controlled by the contact between granites and gneissic country rock. The highest ore concentrations occur, with some exceptions, in greisens and less frequently in the highly greisenised and argillitised topaz granites. The Sn-W mineralisation can be subdivid #contributions #to #mineralization ... https://www.youtube.com/watch?v=0kl4dPSvtvA

Gravity Online Course https://giladjames.com Section: 3D Modeling and Inversion of Gravity Data in Exploration Scale Lesson: Conventional volumetric inversion Gravity. This course is brought to you by Gilad James Mystery School. Learn more at Gilad James.com. Introduction Gravity method is an important geophysical tool for subsurface mapping of the density distributions. The development of high-accuracy instrumentation and stable observation platform since 1980s has made the large scale airborne gravity survey become possible. The interpretation result based on gravity data can be used for mineral and oil exploration. For example, the gravity data has been used to estimate the depth of the sedimentary basin and detect sub-sea basalt which is usually associated with the oil reservoir. The gravity modeling has its origin back to Newton’s law of universal gravitation developed in 1687, which is equivalent to solving a Poisson’s equation for scalar gravity potential. One can use different approaches to solve this Poisson’s equation, e.g., finite difference or finite element method. However, the most common approach is to solve it in an integral way using Green’s function. In the first section of this lecture, we will review the Poisson’s equation and its integral solution for a general three-dimensional case. The numerical approaches to evaluate the integrals in the solution of the Poisson’s equation will be discussed. For more realistic problems, we also provide an approach of gravity modeling to take into account of complex geometry such as topography. Conventional gravity inversion is based on discretizing the earth model into a set of rectangular prisms, and considering each prism has a constant density. Given observed gravity and/or gravity gradiometry fields, one is interested to recover the density within each cell. Similar as other geophysical inverse problems, this volumetric inversion of gravity data is an ill-posed problem which is strongly affected by the non-uniqueness and instability. To solve this ill-posed a problem, we will first introduce an objective functional which contains two parts, the misfit functional for least-square fitting of the observed data, and the stabilizer for regularizing the subsurface density distributions. The solutions for solving the minimization problem of this objective functional will then be briefly discussed. Generally, the volumetric gravity inversion produces diffusive images of the subsurface density distribution with very limited depth resolution (strictly speaking, the gravity method, with observation above the earth’s surface, does not have any depth resolution for the subsurface density distribution). One may improve the gravity inversion results by adding more constraints, e.g., logarithmic barrier to constrain upper and lower limits of the density, focusing stabilizer to produce sharper boundaries between the density contrasts, and etc., in the inversion. A more advanced approach of gravity inversion is to invert for the shape of the anomaly instead of the three-dimensional volumetric density distribution. In certain applications, such as sedimentary basin analysis, it is more interesting to estimate the location of the sediment-basement interface and the shape by assuming that the density distribution of the sediments in vertical direction is known based on some other a priori information such as well logging. To solve this specific problem, the geometric inversion method to recover the depth to basement has been proposed in recent years. These types of methods are mostly based on the discretization of the sedimentary columns or the sediment-basement interface instead of the 3D subsurface. By adopting this new discretization, the parameters of unknown in the inversion and the model uncertainty can be reduced significantly. In the last section of this lecture, we will discuss the most updated geometric modeling and inversion method. #gravity ... https://www.youtube.com/watch?v=h0-C6UT2V24

Boston Celtics https://giladjames.com The Boston Celtics are an American professional basketball team based in Boston. The Celtics compete in the National Basketball Association (NBA) as a member of the league's Eastern Conference Atlantic Division. Founded in 1946 as one of the league's original eight teams, the Celtics play their home games at TD Garden, which they share with the National Hockey League's Boston Bruins. The Celtics are regarded as one of the most successful basketball teams in NBA history; the franchise is tied with the Los Angeles Lakers for most NBA championships won with 17 (accounting for 23.6 percent of all NBA championships since the league's founding) and currently holds the record for the most recorded wins of any NBA team. The Celtics have a notable rivalry with the Los Angeles Lakers, which was heavily highlighted throughout the 1960s and 1980s. During the two teams' many match-ups in the 1980s, the Celtics' star, Larry Bird, and the Lakers' star, Magic Johnson, had an ongoing feud. The franchise has played the Lakers a record 12 times in the NBA Finals (including their most recent appearances in 2008 and 2010), of which the Celtics have won nine. Four Celtics players (Bob Cousy, Bill Russell, Dave Cowens and Larry Bird) have won the NBA Most Valuable Player Award for an NBA record total of 10 MVP awards. Both the nickname "Celtics" and their mascot "Lucky the Leprechaun" are a nod to Boston's historically large Irish population, and also to the Original Celtics, a marquee team prior to the NBA. The Celtics' rise to dominance began in the late 1950s, after coach Red Auerbach acquired center Bill Russell, who would become the cornerstone of the Celtics dynasty, in a draft-day trade in 1956. Led by Russell and point guard Bob Cousy, the Celtics won their first NBA championship in 1957. Russell, along with a talented supporting cast of future Hall of Famers including John Havlicek, Tom Heinsohn, K. C. Jones, Sam Jones, Satch Sanders, and Bill Sharman, would usher the Celtics into the greatest period in franchise history, winning eight consecutive NBA championships from 1959 to 1966. After Russell retired in 1969, the team entered a period of rebuilding. In the mid-1970s, the Celtics became contenders once again, winning two championships in 1974 and 1976 under the leadership of center Dave Cowens and point guard JoJo White. In the 1980s, the Celtics returned to dominance, as well as renewed competition with the "Showtime" Lakers, who were led by Magic Johnson and Kareem Abdul-Jabbar. Anchored by the "Big Three" of Larry Bird, Kevin McHale, and Robert Parish, the Celtics won championships in 1981, 1984, and 1986. The team defeated the Lakers in the 1984 Finals, but lost to Los Angeles in 1985 and 1987. After the departure of Parish as a free agent and the retirement of both Bird and McHale, the team struggled through the 1990s and much of the early 2000s. It was not until the Celtics assembled a new "Big Three" of Kevin Garnett, Paul Pierce, and Ray Allen that they found success once again. Under the leadership of head coach Doc Rivers, the team beat the Lakers to win a championship in 2008, but lost to Los Angeles in a seven-game series in 2010, the latest Finals matchup between the two ancient rivals. By the start of the 2013–14 season, none of the new "Big Three" were still with the team. Garnett and Pierce were traded away to the Brooklyn Nets, while Allen left as a free agent. After a period of rebuilding, the Celtics became a force again under head coach Brad Stevens. During the 2016–17 season, the Celtics clinched the top seed in the Eastern Conference, but were eliminated in the Conference Finals. Led by Jaylen Brown and Jayson Tatum, the team returned to the Conference Finals in 2018 and 2020, but were eliminated both times. Franchise history 1946–1950: Early years The Boston Celtics were formed on June 6, 1946, by Boston Garden-Arena Corporation president Walter A. Brown as a team in the Basketball Association of America, and became part of the National Basketball Association after the absorption of the National Basketball League by the BAA in the fall of 1949. In 1950, the Celtics signed Chuck Cooper, becoming the first NBA franchise to draft a black player. Chuck Connors of The Rifleman fame was an original member of the Celtics in 1946. 1950–1957: Arrival of Bob Cousy and Red Auerbach Bob Cousy played 13 years for the team, 6 of them ending in NBA titles The Celtics struggled during their early years, until the hiring of coach Red Auerbach. In the franchise's early days, Auerbach had no assistants, ran all the practices, did all the scouting—both of opposing teams and college draft prospects—and scheduled all road trips. One of the first great players to join the Celtics was Bob Cousy, whom Auerbach initially refused to draft out of nearby Holy Cross because he was "too flashy". ... https://www.youtube.com/watch?v=Q7yWaMPX9vE

Clays, Clay Minerals and Ceramic Materials Based on Clay Minerals Online Course https://giladjames.com Section: Structure of Clays and Polymer–Clay Composites Studied by X-ray Absorption Spectroscopies Lesson: Clays, clay minerals, and ceramics Clays, Clay Minerals and Ceramic Materials Based on Clay Minerals. This course is brought to you by #clays, #clay #minerals #and #ceramic #materials #based #on #clay #minerals ... https://www.youtube.com/watch?v=aiV5vuFi00A