Basis Of Presentation	9 Months Ended
Sep. 30, 2012
Basis Of Presentation	A. Basis of Presentation – The interim Consolidated Financial Statements of Alcoa Inc. and its subsidiaries (“Alcoa” or the “Company”) are unaudited. These Consolidated Financial Statements include all adjustments, consisting of normal recurring adjustments, considered necessary by management to fairly state the Company’s results of operations, financial position, and cash flows. The results reported in these Consolidated Financial Statements are not necessarily indicative of the results that may be expected for the entire year. The 2011 year-end balance sheet data was derived from audited financial statements but does not include all disclosures required by accounting principles generally accepted in the United States of America (GAAP). This Form 10-Q report should be read in conjunction with Alcoa’s Annual Report on Form 10-K for the year ended December 31, 2011, which includes all disclosures required by GAAP. Deferred mining costs. Alcoa recognizes deferred mining costs during the development stage of a mine life cycle. Such costs include the construction of access and haul roads, detailed drilling and geological analysis to further define the grade and quality of the known bauxite, and overburden removal costs. These costs relate to sections of the related mines where Alcoa is either currently extracting bauxite or is preparing for production in the near term. These sections are outlined and planned incrementally and generally are mined over periods ranging from one to five years, depending on mine specifics. The amount of geological drilling and testing necessary to determine the economic viability of the bauxite deposit being mined is such that the reserves are considered to be proven, and the mining costs are amortized based on this level of reserves. Mineral rights. Alcoa recognizes mineral rights upon specific acquisitions of land that include such underlying rights, primarily in Jamaica. This land is purchased for the sole purpose of mining bauxite. The underlying bauxite reserves are known at the time of acquisition based on associated drilling and analysis and are considered to be proven reserves. The acquisition cost of the land and mineral rights are amortized as the bauxite is produced based on the level of minable tons determined at the time of purchase.

A. Basis of Presentation – The interim Consolidated Financial Statements of Alcoa Inc. and its subsidiaries (“Alcoa” or the “Company”) are unaudited. These Consolidated Financial Statements include all adjustments, consisting of normal recurring adjustments, considered necessary by management to fairly state the Company’s results of operations, financial position, and cash flows. The results reported in these Consolidated Financial Statements are not necessarily indicative of the results that may be expected for the entire year. The 2011 year-end balance sheet data was derived from audited financial statements but does not include all disclosures required by accounting principles generally accepted in the United States of America (GAAP). This Form 10-Q report should be read in conjunction with Alcoa’s Annual Report on Form 10-K for the year ended December 31, 2011, which includes all disclosures required by GAAP.

Deferred mining costs. Alcoa recognizes deferred mining costs during the development stage of a mine life cycle. Such costs include the construction of access and haul roads, detailed drilling and geological analysis to further define the grade and quality of the known bauxite, and overburden removal costs. These costs relate to sections of the related mines where Alcoa is either currently extracting bauxite or is preparing for production in the near term. These sections are outlined and planned incrementally and generally are mined over periods ranging from one to five years, depending on mine specifics. The amount of geological drilling and testing necessary to determine the economic viability of the bauxite deposit being mined is such that the reserves are considered to be proven, and the mining costs are amortized based on this level of reserves.

Mineral rights. Alcoa recognizes mineral rights upon specific acquisitions of land that include such underlying rights, primarily in Jamaica. This land is purchased for the sole purpose of mining bauxite. The underlying bauxite reserves are known at the time of acquisition based on associated drilling and analysis and are considered to be proven reserves. The acquisition cost of the land and mineral rights are amortized as the bauxite is produced based on the level of minable tons determined at the time of purchase.