Talc
Three pieces of Talc.
General
Category	Silicate mineral
Chemical formula	Mg3Si4O10(OH)2
Strunz classification	9.EC.05
Crystal symmetry	Either monoclinic 2m or triclinic 1[1]
Unit cell	a = 5.291 Å, b = 9.173 Å, c = 5.290 Å; α = 98.68°, β = 119.90°, γ = 90.09°; Z = 2 or a = 5.287 Å, b = 9.158 Å, c = 18.95 Å, β = 99.3°; Z = 4[1]
Identification
Color	Light to dark green, brown, white
Crystal habit	Foliated to fibrous masses, rare as platey to pyramidal crystals
Crystal system	monoclinic or triclinic[2]
Cleavage	Perfect on {001} basal cleavage
Fracture	Flat surfaces (not cleavage), fracture in an uneven pattern
Tenacity	Sectile
Mohs scale hardness	1 (defining mineral)
Luster	Waxlike or pearly
Streak	White to pearl green
Diaphaneity	Translucent
Specific gravity	2.58 to 2.83
Optical properties	Biaxial (-)
Refractive index	nα = 1.538 – 1.550 nβ = 1.589 – 1.594 nγ = 1.589 – 1.600
Birefringence	δ = 0.051
Pleochroism	Weak in dark varieties
Ultraviolet fluorescence	Short UV=orange yellow, long UV=yellow
References	[1][3][4]

Talc (derived from the Persian tālk (تالک ), Arabic talk (تلك)) is a mineral composed of hydrated magnesium silicate with the chemical formula H₂Mg₃(SiO₃)₄ or Mg₃Si₄O₁₀(OH)₂. In loose form, it is the widely used substance known as talcum powder. It occurs as foliated to fibrous masses, its crystals being so rare as to be almost unknown. It has a perfect basal cleavage, and the folia are non-elastic, although slightly flexible. It is the softest known mineral and listed as 1 on the Mohs hardness scale. It can be easily scratched by a fingernail. It is also sectile (can be cut with a knife). It has a specific gravity of 2.5–2.8, a clear or dusty luster, and is translucent to opaque. Talc is not soluble in water, but it is slightly soluble in dilute mineral acids. Its colour ranges from white to grey or green and it has a distinctly greasy feel. Its streak is white.

Soapstone is a metamorphic rock composed predominantly of talc.

Formation[link]

A block of talc.

Talc is a metamorphic mineral resulting from the metamorphism of magnesian minerals such as serpentine, pyroxene, amphibole, olivine, in the presence of carbon dioxide and water. This is known as talc carbonation or steatization and produces a suite of rocks known as talc carbonates.

Talc is primarily formed via hydration and carbonation via the following reaction;

serpentine + carbon dioxide → talc + magnesite + water

2 Mg₃Si₂O₅(OH)₄ + 3CO₂ → Mg₃Si₄O₁₀(OH)₂ + 3 MgCO₃ + 3 H₂O

Talc can also be formed via a reaction between dolomite and silica, which is typical of skarnification of dolomites via silica-flooding in contact metamorphic aureoles;

dolomite + silica + water → talc + calcite + carbon dioxide

3 CaMg(CO₃)₂ + 4 SiO₂ + H₂O → Mg₃Si₄O₁₀(OH)₂ + 3 CaCO₃ + 3 CO₂

Talc can also be formed from magnesian chlorite and quartz in blueschist and eclogite metamorphism via the following metamorphic reaction:

chlorite + quartz → kyanite + talc + water

In this reaction, the ratio of talc and kyanite is dependent on aluminium content with more aluminous rocks favoring production of kyanite. This is typically associated with high-pressure, low-temperature minerals such as phengite, garnet, glaucophane within the lower blueschist facies. Such rocks are typically white, friable, and fibrous, and are known as whiteschist.

Talc is a tri-octahedral layered mineral; its structure is similar to that of pyrophyllite, but with magnesium in the octahedral sites of the composite layers.^[2]

Occurrence[link]

Talc output in 2005

Talc is a common metamorphic mineral in metamorphic belts which contain ultramafic rocks, such as soapstone (a high-talc rock), and within whiteschist and blueschist metamorphic terranes. Prime examples of whiteschists include the Franciscan Metamorphic Belt of the western United States, the western European Alps especially in Italy, certain areas of the Musgrave Block, and some collisional orogens such as the Himalayas which stretches along Pakistan, India, Nepal and Bhutan.

Talc carbonate ultramafics are typical of many areas of the Archaean cratons, notably the komatiite belts of the Yilgarn Craton in Western Australia. Talc-carbonate ultramafics are also known from the Lachlan Fold Belt, eastern Australia, from Brazil, the Guiana Shield, and from the ophiolite belts of Turkey, Oman and the Middle East.

Notable economic talc occurrences include the Mount Seabrook talc mine, Western Australia, formed upon a polydeformed, layered ultramafic intrusion. The France-based Luzenac Group is the world's largest supplier of mined talc; its largest talc mine at Trimouns near Luzenac in southern France produces 400,000 tonnes of talc per year, representing 8% of world production.^[5]

Uses[link]

Talcum powder.

The structure of talc is composed of Si₂O₅ sheets with magnesium sandwiched between sheets in octahedral sites.

Talc is used in many industries such as paper making, plastic, paint and coatings, rubber, food, electric cable, pharmaceuticals, cosmetics, ceramics, etc. A coarse grayish-green high-talc rock is soapstone or steatite and has been used for stoves, sinks, electrical switchboards, crayons, soap, etc. It is often used for surfaces of lab counter tops and electrical switchboards because of its resistance to heat, electricity and acids. Talc finds use as a cosmetic (talcum powder), as a lubricant, and as a filler in paper manufacture. Talc is used in baby powder, an astringent powder used for preventing rashes on the area covered by a diaper (see diaper rash). It is also often used in basketball to keep a player's hands dry. Most tailor's chalk, or French chalk, is talc, as is the chalk often used for welding or metalworking.

Talc is also used as food additive or in pharmaceutical products as a glidant. In medicine talc is used as a pleurodesis agent to prevent recurrent pleural effusion or pneumothorax. In the European Union the additive number is E553b.

Talc is widely used in the ceramics industry in both bodies and glazes. In low-fire artware bodies it imparts whiteness and increases thermal expansion to resist crazing. In stonewares, small percentages of talc are used to flux the body and therefore improve strength and vitrification. It is a source of MgO flux in high temperature glazes (to control melting temperature). It is also employed as a matting agent in earthenware glazes and can be used to produce magnesia mattes at high temperatures.

ISO standard for quality (ISO 3262)

Patents are pending on the use of magnesium silicate as a cement substitute. Its production requirements are less energy-intensive than ordinary Portland cement at around 650 °C, while it absorbs far more carbon dioxide as it hardens. This results in a negative carbon footprint overall, as the cement substitute removes 0.6 tonnes of CO₂ per tonne used. This contrasts with a carbon footprint of 0.4 tonne per tonne of conventional cement.^[6]

Talc is sometimes used as an adulterant to illegal heroin, to expand volume and weight and thereby increase its street value. With intravenous use, it may lead to talcosis, a granulomatous inflammation in the lungs.

Safety[link]

Talc powder is a household item, sold globally for use in personal hygiene and cosmetics and used by many millions every year. Some suspicions have been raised about the possibility its use promotes certain types of diseases, mainly cancers of the ovaries and lungs. This is not widely recognised as an established link.^[7][8]

The studies reference, by subject: pulmonary issues,^[9] lung cancer,^[10][11] skin cancer and ovarian cancer.^[12] One of these, published in 1993, was a US National Toxicology Program report, which found that cosmetic grade talc containing no asbestos-like fibres was correlated with tumour formation in rats (animal testing) forced to inhale talc for 6 hours a day, five days a week over at least 113 weeks.^[10] A 1971 paper found particles of talc embedded in 75% of the ovarian tumors studied.^[13]

The US Food and Drug Administration (FDA) considers talc (magnesium silicate) to be generally recognized as safe (GRAS) for use as an anti-caking agent in table salt in concentrations smaller than 2%.^[14]

See also[link]

References[link]

External links[link]

Wikimedia Commons has media related to: Talc

• mineral.galleries.com

Professor Layton (レイトン教授, Reiton-kyōju^?) is a puzzle adventure game^[1] series for the Nintendo DS and Nintendo 3DS developed by Level-5. The series currently consists of five games and one film. A sixth game and another movie is currently being planned. A crossover game titled Professor Layton vs. Ace Attorney is also in development for the Nintendo 3DS. The first three games are about Professor Hershel Layton and Luke Triton's adventures together. The next three games and the two films are prequels and are about how Luke and Layton met and their "original" adventures.

Each title is based in a series of puzzles and mysteries given by the citizens of towns that the main characters visit. It is not necessary to solve all the puzzles to progress, but some are mandatory and at certain points in the game a minimum number of puzzles must be solved before the story will continue.

The series has gone on to be one of the most successful Nintendo DS exclusive series, with the lifetime cumulative sales of Professor Layton games standing at 10 million units sold as of October 2010.^[2] As of March 2012, the series has sold over 13 million copies.^[3]

History[link]

Professor Layton was a direct result of Akihiro Hino's childhood love of Akira Tago's popular Head Gymnastics series of puzzle books, which have sold more than 12 million copies to date in Japan.

The main character in the games is Professor Hershel Layton, a renowned archaeologist and a well-mannered gentleman. He is called to solve various mysteries in different places. Professor Layton is always accompanied by his apprentice Luke Triton, a cheerful and curious boy who brings a touch of humor to the story of Layton. According to Hino, Layton is partly inspired by the character of Phoenix Wright of the Ace Attorney series, wanting to improve over the "bad points" of Phoenix's character in developing Layton.^[4]

Games[link]

1. Professor Layton and the Curious Village (レイトン教授と不思議な町^?)^[5]
2. Professor Layton and the Diabolical Box (レイトン教授と悪魔の箱^?)^[6]
3. Professor Layton and the Unwound Future (レイトン教授と最後の時間旅行^?)
4. Professor Layton and the Last Specter (レイトン教授と魔神の笛^?)
5. Professor Layton and the Miracle Mask (レイトン教授と奇跡の仮面^?)

There was also a "Friendly Version" for The Curious Village, from which all weekly puzzles are unlocked, as well as the game being slightly easier for those who were troubled previously. For Diabolical Box, the Japan-only "Level-5 Premium Silver/Gold" collections on Nintendo DS included an exclusive side-story, "Professor Layton and the London Holiday" (レイトン教授とロンドンの休日^?) in addition to the actual game and another Level-5 game, Inazuma Eleven. The Holiday in London includes ten puzzles, some of which are from the first game, and a short storyline, set in Professor Layton's London office, in which he reminisces about his previous adventures around the world.

A new mobile phone Professor Layton game is intended for release around the same time as the fifth game. However it is unknown if and when the game will get an international release.

Professor Layton vs. Ace Attorney is a crossover game between the Ace Attorney series and the Professor Layton series; it is being co-developed by Capcom and Level-5 for the Nintendo 3DS. It is described as a combination of the two game styles - puzzle solving and crime investigation. Shu Takumi, the main writer of the original Ace Attorney games, will be writing the script for this title.^[7]

Setting and characters[link]

The game takes place in and around contemporary London. The titular character is Hershel Layton, a professor of archeology at the fictional Gressenheller University, who prides himself on gentlemanly conduct and puzzle mastery. He is often followed by his self-proclaimed apprentice, the young Luke Triton, who also proves adept at solving puzzles. Following the events of The Curious Village, Layton is joined by Flora Reinhold who helps to tend his university offices but also seeks to go on Layton's adventures. Layton's mysteries often run him into the police chief of Scotland Yard, Inspector Chelmey. Layton also encounters a gifted inventor named Don Paolo (aka Paul), who is a master of disguise; he claims to be the nemesis of Layton, due to losing the love of his life, Claire, to Layton's charms. During the prequel trilogy, Layton's former assistant, Emmy Altava, joins up with him and Luke.

Plot[link]

The games and other media in the Professor Layton series do not have any overarching structure or direct connection to each other, but do follow a chronological order through the appearance of reoccurring characters met in earlier works.

[edit] The Curious Village

The first game in the series, released for the Nintendo DS in Japan during 2007 and localized elsewhere during 2008. Layton and his young apprentice Luke are invited to the town of St. Mystere by the family of late Baron Augustus Reinhold to figure out the secret behind his last will and testament, in which he stated that anyone who found the Golden Apple hidden within the town would be entitled to his entire fortune. Upon entering the town, it is clear to both of them that the curious village holds many more secrets than they had expected. They solve their way through 138 puzzles to discover the truth behind St. Mystere.

[edit] The Diabolical Box

The second game in the series, released for the Nintendo DS in Japan during 2007 and localized elsewhere during 2009. It is known in PAL regions as Professor Layton and Pandora's Box. It begins with the Professor and Luke traveling to meet Layton's mentor, Dr. Schrader, who has sent the pair a letter detailing his procuring of the Elysian Box, a chest rumored to kill anyone who tried to open it. Upon walking into his apartment, he is found lying on the floor, dead, with the box missing. The only clue he left behind was a train ticket for the high-class Molentary Express without a mentioned destination, which they promptly catch to begin their investigation to find out more on the fate of Dr. Schrader, and the whereabouts of his diabolical box. During their search, they encounter 153 additional puzzles.

[edit] The Unwound Future

The third game in the series, released for the Nintendo DS in Japan during 2008 and localized elsewhere during 2010. It is known in PAL regions as Professor Layton and the Lost Future. The game starts upon Luke receiving a letter purportedly sent by himself, ten years into the future, only a week after an accident in which Dr. Stahngun's failed demonstration of a time machine caused himself and the Prime Minister to vanish. He and Layton travel to a desolate part of town to investigate a clock shop, but upon walking out, find themselves to have been thrust forward into the future London, ten years from then. In their efforts to find the truth of their unwound future, they are forced to solve 168 new puzzles, and to remember a forgotten past. This game is currently the last in the series chronologically.

[edit] The Last Specter

The fourth game in the series was released for the Nintendo DS in Japan during 2009 and North America on October 17, 2011. It is known in Europe as Professor Layton and the Spectre's Call. It is, chronologically, the first game in the series, in which Layton is called by an old friend named Clark to the mysterious, dark, and foggy town of Misthallery, where legends exist of a great, shadowy giant who protects the region whenever a special flute is played to summon him. However, recently, the figure has turned against the village, and it is up to the Professor, a young boy of the village named Luke Triton who is heavily involved in the legend of the Specter, and Layton's new assistant Emmy Altava, to figure out why the specter is wreaking havoc in the town. Together, they investigate the village and the Last Specter, and, while doing so, solve another 170 puzzles. In the USA and Japan, the game also includes an RPG called London Life, which was co-developed by Brownie Brown. It was excluded from the EU version due to 'time constraints'.

[edit] The Eternal Diva

The first movie based on the games, released in Japan during 2009 and in the United Kingdom during 2010. Chronologically, the events in the story take place after Last Specter, though the story is told as a flashback at some point between Curious Village and Diabolical Box (being the events of the flashback story took place 3 years prior). Emmy joins with Layton and Luke on a journey to meet Janice Quatlane, a previous student of Professor Layton experiencing success as an opera singer. One of her friends, Melina, a seven-year-old girl, claimed she had found eternal life. While investigating, Layton, Luke, and Janice become trapped on the ship, the Crown Petone, and are forced to cooperate with Descole's plans to restore the lost city of Ambrosia. Meanwhile, Emmy investigates mysterious disappearances of children around London. Many characters from the games make a cameo appearance, as does the Elysian Box itself. Over the course of the movie, the cast will solve four puzzles...

[edit] The Miracle Mask

The fifth game in the series, released as a launch title for the Nintendo 3DS on February 26, 2011 in Japan, and was confirmed for an eventual release in North America, Australia and Europe at E3 2010. Professor Layton and Luke follow Jean Descole to a place known as Montdol in search of a powerful mask said to have created the city. Professor Layton is forced to recall his past in order to uncover the secret of the mask in the present. The truth is hidden deep within the Miracle Mask. Level-5 claims that the game will have daily puzzles available for download over Nintendo Wi-Fi Connection for a full year.^[8]

[edit] Professor Layton vs. Ace Attorney

Announced on October 19, 2010 at Level-5's annual vision event, this game, also unofficially referred to as Professor Layton vs Ace Attorney, is a cooperative project between Level-5 and Capcom, and a crossover between the Professor Layton and Ace Attorney series. In it, Professor Layton, Luke, Phoenix Wright, and Maya Fey, find themselves in a medieval world separate from both of their own, known as Labyrinth City. This world is controlled by a man known as the Storyteller, who can make anything he writes down a reality. The land also speaks tales of witches, who hide in the shadows. It will be released in Japan for the Nintendo 3DS during 2012.

[edit] Future entries

Level-5 confirmed a 6th and final game for the second trilogy is in production which will take place after Miracle Mask and the second movie chronologically. No title has been confirmed as of yet. ^[9]

An iOS video game, Layton Brothers Mystery Room (レイトンブラザーズ・ミステリールーム, Reiton Burazāzu Misuterī Rūmu^?), is currently being developed and will feature Hershel Layton's son, Alfendy Layton.^[10]

Level 5 CEO Akihiro Hino has expressed interest in porting the series to Wii U.^[11]

Another mobile game was announced, named "Layton Royale", which is a social RPG allowing players to play as the heroes and villains of the Layton universe.

Additionally, there are plans for two further movies. One of these is stated to be an animated addition to the prequel trilogy like Eternal Diva before it, and the other is planned to be filmed in live-action.^[12]

Gameplay[link]

The game is essentially a collection of puzzles with exploration sections between them. The player, as Professor Layton and Luke, explore their environments in a point-and-click adventure game fashion using the DS's touchscreen. This can be used to talk with non-player characters, learn more about the environment, moving between different areas, or to find hint coins that are used during puzzles. Often, when interacting with a person or object, the player will be presented with a puzzle, valued at a number of "picarats", a type of currency within the game. Solving the puzzle correctly will earn the player that many picarats, but a wrong answer will reduce the value a small amount on subsequent attempts down to a minimal picarat number. In order to progress the plot, the player is required to solve specific puzzles, or to solve a minimum number of puzzles or gain a minimum amount of picarats. When the player leaves an area due to progression of the plot, puzzles they have yet to find or solve are collected into another location where they can return and attempt to resolve later. Curious Village contains 135 puzzles, Diabolical Box contains 153 puzzles, Unwound Future contains 168 (The later two having another special puzzle obtained via the use of codes found in the previous game), and Last Specter contains 170.

The puzzles take the form of brain teasers and are only loosely tied to the plot. All puzzles were created for this series by Akira Tago, who is famous for his best-selling Mental Gymnastics series. They take the forms of math problems, logic puzzles, mazes, sliding-block puzzles, and brain teasers. The games give the player the opportunity to bring up a translucent memo screen they can write on using the stylus to work out their answer before submission. If the player is stuck, they may spend one hint coin to receive a hint. Each puzzle has three hints available, and within The Unwound Future, the game introduces "super hints" that nearly solve the puzzle for the player but which can only be bought with two hint coins and after the three other hints have been revealed. The puzzles are not timed, though for puzzles such as mazes or sliding blocks, the player may be challenged to complete the puzzle in a limited number of moves.

Each game features an additional set of three unique meta-puzzles that can be accessed at any time through "Layton's Trunk". These puzzles generally require the player to complete specific puzzles in the game to receive items to use within the meta puzzle; for example, The Curious Village gives the player furniture as a reward for some puzzles, which then must be placed within a set of apartments to Layton's and Luke's exacting desires in the meta puzzle; the meta puzzle cannot be solved completely until all the furniture has been collected. Completing the game also opens a number of series of more difficult puzzles to be solved, including one that involves a curiously heavily-locked door that the player may encounter during the game. The games also can use the DS Nintendo Wi-Fi Connection features to connect to Nintendo world network and unlock additional puzzles for play for a number of weeks after each game's release.

Other media[link]

Manga[link]

Manga intended for child audiences has been serialized since the February 2008 special edition of Bessatsu CoroCoro Comic. The title of this manga is Professor Layton and the Cheerful Mystery (レイトン教授とユカイな事件, Reiton-kyōju to yukai na jiken^?), covering many mysteries in the story. Three volumes have been released as of June 2011.

Feature film[link]

An animation film called Professor Layton and the Eternal Diva was produced by Masakazu Kubo, who is mainly known for producing the Pokémon films, and animated by P.A. Works, the same company that develops the animated cutscenes for the games. It contains an original story, separate from the game series,^[6] and taking place after the events of The Last Specter. It has been a general success in both Japan and Singapore where the movie was released. The film was released in the United Kingdom on DVD and Blu-ray by Manga Entertainment on October 18, 2010.^[13]

Novels[link]

Three books based on the Professor Layton series were also made, though they are still in Japan only. They consist of Professor Layton and the Wandering Castle in 2008, Professor Layton and the Phantom Deity in 2009, and Professor Layton and the Illusory Forest in 2010.

Reception[link]

The Professor Layton series has been generally successful in the UK, the US, and Japan. Professor Layton and the Curious Village sold over 700,000 units in Japan in 2007.^[22] The game was also the top selling game for the Nintendo DS in the United States in the first three weeks after its release. After it was restocked in the UK, sales of Professor Layton increased 54%, moving it from 10th place to fourth place.

Curious Village received generally positive reviews from critics. On the review aggregator Game Rankings, the game had an average score of 86% based on 48 reviews. On Metacritic, the game had an average score of 85/100, based on 57 reviews. The combination of the adventure game and "brain training" genres received mixed appreciation. Some reviewers praised the game for the successful combination with 1UP commenting on how the game's approach is much better than games where the puzzles were integrated into the environment. Other reviewers felt that these two genres do not merge well within the game; Game Informer noted that while the player is given numerous small puzzles to solve, the mysteries of the main plot are basically solved for the player. The game was noted to have little replay value; once all the puzzles were solved, there was no point in playing through them again. The presentation of the game, including both the general European animation style and cutscene animations, was appreciated by reviewers. Hyper's Darren Wells commends the game for its "clever concept, with plenty to solve and unlock as well as its fantastic presentation". However, he criticizes "some puzzles feeling tacked on and the music can get annoying".

Professor Layton and the Diabolical Box was considered to be a major improvement from the original. In Japan, the game has sold 815,369 copies, according to Famitsu, as of July 9, 2008.^[23] The UK's Official Nintendo Magazine awarded the game a score of 92% (and consequently their Gold Award medal), praising the increased number of puzzles, animated scenes and voice acting, but complained that it could be slightly repetitive at times. IGN gave the game a score of 8.5 and also their Editor's Choice Award.

The series was popular enough to have a movie called Professor Layton and the Eternal Diva made. So far it has only been released in Japan, Singapore, France, Germany and the UK, but was recently (2011) released in America and Canada. It received positive reviews from the first five countries, but has not yet been talked about in reviews in America and Canada. It was released in the UK on the 18th of October, with a full English Dub.^[24]

Nintendo Power listed series mascot Professor Layton as their 10th favorite hero, citing his use of brains over brawn.^[25]

The series has gone on to be one of the most successful Nintendo DS exclusive series, with the lifetime cumulative sales of Professor Layton games standing at 10 million units sold as of October 2010.^[2] Level-5 reported 11.47 million unit sales worldwide for the franchisee ahead of the release of Professor Layton and the Miracle Mask in February 2011,^[26] and over 13 million copies sold in March 2012.^[3]

References[link]

External links[link]

• Professor Layton series official North American site
• Professor Layton and the Eternal Diva official Japanese site (Japanese)
• Professor Layton and the Eternal Diva official UK site