Question: In April 2015 Fuganto Widjaja revealed a surprise takeover bid for a mining company founded by a man that is chairman of what company?

Context articles: Bankmail
Nathaniel Philip Rothschild
James MacNaughton
Rockwell Diamonds
Isle of Man Mining Company
Fuganto Widjaja
Vodafone Kabel Deutschland
Phelps Dodge
Dempo
Anaconda Copper

In a bankmail agreement, a company engaged in a takeover bid makes an agreement with a bank that the bank would only finance their possible bid, and not that of a rival attempt to acquire the takeover target.
Nathaniel Philip Victor James "Nat" Rothschild (born 12 July 1971) is a British-born financier who has settled in Switzerland, and a member of the prominent Rothschild family.
 He is chairman of JNR Limited, an investment advisory business primarily focused on emerging markets in the metals, mining and resources sector.
 He was co-chairman of Asia Resource Minerals PLC, a natural resources group, that he helped create and that is listed on the London Stock Exchange.
 He was co-chairman of the hedge fund Atticus Capital from 1996 until its dissolution in 2009.
 He has a wide range of international business interests.
James MacNaughton, also variously known as "the King of Houghton County", the "Czar of the Copper Country" or simply "Big Jim" (b. March 4, 1864) was the third and last known President and General Manager of the Calumet and Hecla Mining Company during the hate-filled Copper Country Strike of 1913–1914.
 In addition to the Calumet and Hecla Mining Company, MacNaughton was also the General Manager of the Ahmeek Mining Company, Allouez Mining Company, North Kearsarge mine, South Kearsarge mine, Tamarack Mining Company, Osceola Consolidated Copper Company, St. Louis Copper Company, Laurium Mining Company, La Salle Copper Company, Isle Royale Copper Company, Superior Copper Company, and the Centennial Copper Mining Company.
 MacNaughton also held a position as the Chairman of the Houghton County Board of Supervisors and the first chairman of Miscowaubik, a private business club headquartered in Calumet, Michigan.
Rockwell Diamonds is a mid-tier diamond mining and development company.
 The company has an interest in producing and exploration alluvial diamond properties in southern Africa.
 The stocks of the company trade on South African, Canadian, and American exchanges.
 The company was recently in the news due to a hostile takeover bid that was attempted by Pala Investments Holdings Limited.
The Isle of Man Mining Company also referred to as the Foxdale Mining Company was a mining company formed to operate the Foxdale Mines on the Isle of Man.
Fuganto Widjaja is the grandson of Eka Tjipta Widjaja, the founder of the Sinar Mas Group, an Indonesian palm oil and property conglomerate started before the Second World War.
 In April 2015, he revealed a surprise takeover bid for Asia Resource Minerals, the coal mining company founded by Nathaniel Philip Rothschild.
Vodafone Kabel Deutschland is the largest cable television operator in Germany.
 Kabel Deutschland was subject to a hostile takeover bid by the British Vodafone Group in September 2013; the deal was approved in December 2013 and finalised on 29 January 2014.
 Until the takeover the company name was "Kabel Deutschland".
Phelps Dodge Corporation was an American mining company founded in 1834 as an import-export firm by Anson Greene Phelps and his two British sons-in-law William Earle Dodge, Sr. and Daniel James.
 The latter two ran Phelp, James & Co., the part of the organization based in Liverpool, England.
 The import-export firm at first exported United States cotton from the Deep South to England, and imported various metals to the US needed for industrialization.
 With the expansion of the western frontier in North America, the corporation acquired mines and mining companies, including the Copper Queen Mine in Arizona and the Dawson, New Mexico coal mines.
 It operated its own mines and acquired railroads to carry its products.
 By the late 19th century, it was known as a mining company.
Dempo Mining Corporation Limited is a prominent mining company from the western Indian state of Goa, thanks to Mr. M.M.P. D' Souza (one of the founders of the mining industry in Goa).
 This company was built from Souza Mineralia Pvt. Ltd.
 The mineral business was founded by Mr. Vasantrao S. Dempo in 1941 along with his younger brother Mr. Vaikuntrao Dempo.
 Mr. Vasantrao S. Dempo was the Founder Chairman of the company, who was succeeded by his son Mr. Vasudeva V. Dempo.
 Currently Shrinivas V. Dempo, son of Mr. Vasudeva V. Dempo is the chairman of Dempo Group.
 Dempo Sports Club is linked to Dempo mining company.
 Dempo company has interests in many fields and the umbrella company is known as V.S. Dempo & Co.
 In June 2011, Vedanta Limited acquired Dempo Group's mining assets for () .
Anaconda Copper Mining Company (from 1899 to 1915, known as the Amalgamated Copper Mining Company) was an American mining company.
 It was one of the largest trusts of the early 20th century.
 Founded in 1881 when Marcus Daly bought a silver mine, the company expanded rapidly based on the discovery of huge copper deposits.
 Daly built a smelter to process copper mined in Butte, Montana.
 By 1910, Anaconda had expanded its operations and bought the assets of two other Montana copper companies.
 In 1922 it bought mining operations in Mexico and Chile; the latter was the largest mine in the world and yielded two-thirds of the company's profits.
 The company added aluminum reduction to its portfolio in 1955.