Amphibole is an important group of inosilicate minerals, forming prism or needlelike crystals, composed of double chain SiO4 tetrahedra, linked at the vertices and containing ions of iron and/or magnesium in their structures. Amphiboles can be green, colorless, yellow, blue, or brown; the International Mineralogical Association classifies amphiboles as a mineral supergroup, within which are two groups and several subgroups. Amphiboles crystallize into two crystal systems and orthorhombic. In chemical composition and general characteristics they are similar to the pyroxenes; the chief differences from pyroxenes are that amphiboles contain essential hydroxyl or halogen and the basic structure is a double chain of tetrahedra. Most apparent, in hand specimens, is that amphiboles form oblique cleavage planes, whereas pyroxenes have cleavage angles of 90 degrees. Amphiboles are specifically less dense than the corresponding pyroxenes. In optical characteristics, many amphiboles are distinguished by their stronger pleochroism and by the smaller angle of extinction on the plane of symmetry.
Amphiboles are the primary constituent of amphibolites. Amphiboles are minerals of either metamorphic origin. Calcium is sometimes a constituent of occurring amphiboles; those of metamorphic origin include examples such as those developed in limestones by contact metamorphism and those formed by the alteration of other ferromagnesian minerals. Pseudomorphs of amphibole after pyroxene are known as uralite; the name amphibole was used by René Just Haüy to include tremolite and hornblende. The group was so named by Haüy in allusion to the protean variety, in composition and appearance, assumed by its minerals; this term has since been applied to the whole group. Numerous sub-species and varieties are distinguished, the more important of which are tabulated below in two series; the formulae of each will be seen to be built on the general double-chain silicate formula RSi4O11. Four of the amphibole minerals are among the minerals called asbestos; these are: anthophyllite, cummingtonite/grunerite series, actinolite/tremolite series.
The cummingtonite/grunerite series is termed amosite or brown asbestos. These are called amphibole asbestos. Mining and prolonged use of these minerals can cause serious illnesses. Orthorhombic series Anthophyllite, 7Si8O222 Holmquistite, Li2Mg3Al2Si8O222 Ferrogedrite, Fe2+5Al4Si6O222Monoclinic series Tremolite, Ca2Mg5Si8O222 Actinolite, Ca25Si8O222 Cummingtonite, Fe2Mg5Si8O222 Grunerite, Fe7Si8O222 Hornblende, 0-1258O222 Glaucophane, Na23Al2Si8O222 Riebeckite, Na2Fe2+3Fe3+2Si8O222 Arfvedsonite, Na3Fe2+4Fe3+Si8O222 Richterite, Na2Ca5Si8O222 Pargasite, NaCa2Mg3Fe2+Si6Al3O222 Winchite, Mg4Si8O222 Edenite, NaCa2Mg5O222 On account of the wide variations in chemical composition, the different members vary in properties and general appearance. Anthophyllite occurs as brownish, fibrous or lamellar masses with hornblende in mica-schist at Kongsberg in Norway and some other localities. An aluminous related species is known as gedrite and a deep green Russian variety containing little iron as kupfferite.
Hornblende is an important constituent of many igneous rocks. It is an important constituent of amphibolites formed by metamorphism of basalt. Actinolite is an important and common member of the monoclinic series, forming radiating groups of acicular crystals of a bright green or greyish-green color, it occurs as a constituent of greenschists. The name is a translation of the old German word Strahlstein. Glaucophane, crocidolite and arfvedsonite form a somewhat special group of alkali-amphiboles; the first two are blue fibrous minerals, with glaucophane occurring in blueschists and crocidolite in ironstone formations, both resulting from dynamo-metamorphic processes. The latter two are dark green minerals, which occur as original constituents of igneous rocks rich in sodium, such as nepheline-syenite and phonolite. Pargasite is a rare magnesium-rich amphibole with essential sodium found in ultramafic rocks. For instance, it occurs in uncommon mantle xenoliths, carried up by kimberlite, it is hard, dense and automorphic, with a red-brown pleochroism in petrographic thin section.
List of minerals Classification of minerals - Silicates C. Michael Hogan. 2010. Calcium. Eds. A. Jorgensen, C. Cleveland. Encyclopedia of Earth. National Council for Science and the Environment. Cornelius S. Hurlbut and Cornelis Klein. 1985. Manual of Mineralogy, 20th ed. John Wiley and Sons, New York ISBN 0-471-80580-7
Raffaello Petrucci was a Cardinal and Roman Catholic bishop. He was born in Siena, circa 1472, he was the son of Giacoppo Petrucci. Since 1494, the year of the Florence Family Doctors' expulsion, he represented the pro-Medici party, advocating for Piero de Medici and his attempts to return home. Between 1495 - 1497, he handled negotiations with the Republic of Siena, aimed at obtaining military support, at a stage where the Republic of Florence had to deal with the rebellion of Pisa and of Montepulciano, with the campaign by Bartolomeo d'Alviano on behalf of the Republic of Venice, which targeted Casentino. In 1497, his father died and on August 4, he was elected as bishop of Grosseto, his tenure in Siena was discreet because of is uncle Pandolfo's preponderance, after the agreements signed between the Republic of Siena and Florence in 1498, came to take on the role of leading citizen or Primus. Politically, the agreement between the two Republics sanctioned the defeat of both Venetian Niccolo Borghesi and pro-Medicean Raffaele Petrucci.
He moved to Rome to follow Cardinal Giovanni de Medici, remaining bound to him in his years of exile, under the pontificates of Alexander VI and Julius II. The election of Cardinal Medici to the papacy in March 1513, opened up the possibility of him taking on a more active role in papal policy concerning disagreements between cousins Borghese and Alfonso with Leo X; this led as party leader. In March 1516, with the support of the Pope and Florence, he implemented a coup that brought him to power but, in the wake of greater Church responsibility, was forced to cede control to his nephew, Francesco in 1522. On 1 July 1517, during the confused events surrounding the "conspiracy of the cardinals", his name was included among the 31 new cardinal appointments of Leo X. On the 26 December he received the title of Santa Susanna. On 14 March 1519 he was appointed apostolic administrator of Bertinoro, keeping the job one year, he took the position of Abbot of San Galgano. On 6 February 1520 he was elected bishop of Sovana.
From the conclave that brought on the election of Adrian VI as Pope, Raffaello was named one of the cardinals in charge of welcoming the new Pope from Utrecht. That year, Renzo da Ceri attempted a new invasion of the territories of the Republic; the past two years, he enlisted his cousin Francis Camillo Petrucci of Siena to govern in his moments of absence. He is buried in the basilica of San Domenico in Siena. Maurizio Gattoni, Pandolfo Petrucci and the Republic of Siena, Cantagalli 1997. III, Holm 2000, p. 215-222. Continuity Republican at the time of Petrucci by Betti Publishing, Siena, 2002, reprinted 2006. Ugurgieri-Azzolini, pumps Siena, Pistoia 1649. Cheney, David M. "Raffaello Cardinal Petrucci". Catholic-Hierarchy.org. Retrieved June 16, 2018
GPU switching is a mechanism used on computers with multiple graphic controllers. This mechanism allows the user to either maximize the graphic performance or prolong battery life by switching between the graphic cards. It's used on gaming laptops which have an integrated graphic device and a discrete video card. Most computers using this feature contain integrated graphics processors and dedicated graphics cards that applies to the following categories. Known as: Integrated graphics, shared graphics solutions, integrated graphics processors or unified memory architecture; this kind of graphics processors have much fewer processing units and share the same memory with the CPU. Sometimes the graphics processors are integrated onto a motherboard, it is known as: on-board graphics. A motherboard with on-board graphics processors doesn't require a discrete graphics card or a CPU with graphics processors to operate. Known as: discrete graphics cards. Unlike integrated graphics, dedicated graphics cards have much more processing units and have its own RAM with much higher memory bandwidth.
In some cases, a dedicated graphics chip can be integrated onto the motherboards, B150-GP104 for example. Regardless of the fact that the graphics chip is integrated, it is still counted as a dedicated graphics cards system because the graphics chip is integrated with its own memory. Most computers have a motherboard that uses a Northbridge structure; the Northbridge is one of the core logic chipset that handles communications among the CPU, GPU, RAM and the Southbridge. The discrete graphics card is installed onto the graphics card slot and the integrated graphics is integrated onto the CPU or onto the Northbridge; the Northbridge is the most responsible for switching between GPUs. The way how it works has the following process: The Northbridge receives input from Southbridge through the internal bus; the Northbridge passes down the input to CPU through the Front-side bus. The CPU runs the task assignment application to determine; the CPU passes down the command to the Northbridge. The Northbridge passes down the command to the according GPU core.
The GPU core returns the rendered data back to the Northbridge. The Northbridge sends the rendered data back to Southbridge; the Southbridge is named as I/O Controller Hub. It handles all of a computer's I/O functions, such as receiving the keyboard input and outputting the data onto the screen; the way how it works has two steps: Take in the user input and pass it down to the Northbridge. Receive the rendered data from the Northbridge and output it; the reason why the second step can be optional is that sometimes the rendered the data is outputted directly from the discrete graphics card, located on the graphics card slot so there is no need to output the data through the Southbridge. GPU switching is used for saving energy by switching between graphic cards; the dedicated graphics cards consume much more power than integrated graphics but provides higher 3D performances, needed for a better gaming and CAD experience. Following is a list of the TDPs of the most popular CPU with integrated graphics and dedicated graphics cards.
The dedicated graphics cards exhibit much higher power consumption than the integrated graphics on both platforms. Disabling them when no heavy graphics processing is needed can lower the power consumption. Nvidia Optimus™ is a computer GPU switching technology created by Nvidia that can dynamically and seamlessly switch between two graphic cards based on running programs. AMD Enduro™ is a collective brand developed by AMD that features many new technologies that can save power, it was named as: PowerXpress and Dynamic Switchable Graphics. This technology implements a sophisticated system to predict the potential usage need for graphics cards and switch between graphics cards based on predicted need; this technology introduces a new power control plan that allows the discrete graphics cards consume no energy when idling. In personal computers, the IGP are manufactured by Intel and AMD and are integrated onto their CPUs, they are known as: Intel HD and Iris Graphics - called HD series and Iris series AMD Accelerated Processing Unit - formerly known as: fusion The most popular dedicated graphics cards are manufactured by AMD and Nvidia.
They are known as: AMD Radeon Nvidia GeForce Most common operating systems have built-in support for this feature. However, the users may download the updated drivers from AMD for better experience. Windows 7 has built-in support for this feature; the system automatically switches between GPUs depending on the program. However, the user may switch the GPUs manually through power manager. In the Linux systems, a patch named vga_switcheroo has been added to the Linux kernel since version 2.6.34 in order to deal with multiple GPUs. Here, the switch requires a restart of the X Window System to be taken into account. Ubuntu Control Center allows the user to access vga_switcheroo functionality through a GUI. Mac OS has built-in support for this feature since v10.5 Leopard. Since OS X Mountain Lion, Apple has integrated the GPU monitor into the Activity Monitor. System incompatibility or unstable power supply may cause Blue Screen of Death or other bugs Unable to switch if the system wrongly estimated the required computing resource Switching may cause unstable voltage which can lead to flashy screen Inconsistent drivers across vendors for smooth switching Graphics processing unit Nvidia Optimus ATI Hy