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Tri-Valley Acquires Admiral Calder Calcium Mine From Sealaska

Tri-Valley Corporation (AMEX: TIV) through its wholly owned subsidiary Select Resources Corporation, Inc. has purchased the Admiral Calder Calcium Carbonate Mine and associated assets from Sealaska Corporation and SeaCal, LLC.

The property is located on the northwestern coast of Prince of Wales Island, part of the Alexander Archipelago in southeast Alaska between Juneau and Ketchikan. The Mine, deposit and local geographic features are named after Rear-Admiral Robert Calder, a British naval officer who served under Horatio Nelson and fought a number of successful actions against the French during the Napoleonic Wars. Select will be calling the Mine and operation the "Admiral," representing its history and maritime location.

The original deposit was discovered around 1905 and mining commenced in 1907 for high white and statuary grade marble. The original quarries ceased operation in about 1910. The current mine began production by Sealaska and SeaCal in 1999.

The Mine consists of 13.9 million tons of drill proven and probable reserves and 12.5 million tons of possible resources of high chemical grade (+98%), high brightness and whiteness (+95 Hunter brightness @ -200 mesh) calcium carbonate for use in the paper, plastics and paint filler, whitener, extender and loader markets. In addition, the property also contains +20 million tons of possible resources of high chemical grade (+98%) and medium brightness (+89 Hunter brightness @ -200 mesh) calcium carbonate for use in chemical applications and as off-white fillers, loaders and extenders. The current Mine covers only 15 acres; the entire property covers 572 acres of patented mining ground, and includes all operating permits and tideland leases. Only about 10% of the property has been explored.

Demand for high grade calcium carbonate is growing in the Pacific Northwest, California and Asian markets, and the Admiral deposit and associated assets are well situated to serve coastal consumers. A significant portion of the calcium carbonate supplied to these locations is imported.

Infrastructure associated with the Mine includes a material handling and crushing circuit, a deepwater shiploader (2,000 tons per hour) and docking barge with +40 feet of draft for inter-coastal barges up to Handy Class (45,000 dwt) sized vessels, lab, shops and offices, mine camp, and various pieces of mining and operating equipment.

Dr. Harold Noyes, President of Select, noted that the Admiral acquisition strengthens Select's industrial mineral assets, and it positions Select to begin penetrating the growing Asian market, including China, with high-grade calcium carbonate. Dr Noyes, who has over 20 years mineral exploration and development experience on Native and public lands in Alaska, also added, "the Admiral Mine acquisition significantly adds to the portfolio of mineral projects Select is building in Alaska and demonstrates our commitment to responsible mineral development in the State."

"The high quality of material, developed mine and infrastructure, deepwater access, and proximity to domestic and international markets position the Admiral Mine to be a significant supplier of high grade calcium carbonate to the Pacific marketplace for the foreseeable future," said Dr. Henry J. Sandri, Executive Vice President of Select.

Sealaska President and CEO, Chris McNeil, complimented Select on the acquisition of the Mine property. "The plans for the Mine will benefit the economy of the Prince of Wales Island and create new jobs leading to further diversification of the Island's economy." Mr. McNeil added that, "The sale is the culmination of a several year effort to sell the Mine. We are pleased with the result and believe that Select will be an excellent new company operating in southeast Alaska."

"We believe this acquisition represents a strong advance in our quest to grow the value of Tri-Valley shares and position Select for high grade markets on a hemispheric basis," said F. Lynn Blystone, president and chief executive officer of the publicly traded parent, Tri-Valley Corporation.

Select Resources Corporation, Inc. -- a wholly owned subsidiary of Tri-Valley Corporation, Inc. -- is involved in the exploration, development and production of precious and base metals, industrial minerals and construction materials with operations and properties in the western U.S. and Canada.

Sealaska Corporation is the Alaska Native Regional Corporation for Southeast Alaska, formed under the Alaska Natives Claims Settlement Act. SeaCal, LLC is Sealaska's wholly owned subsidiary, formed to develop the calcium carbonate deposits subject to this sale.

Tri-Valley is in its 43rd year of business as a successful operating company and for 32 years has been a full reporting 12 (g) publicly traded Delaware Corporation. Tri-Valley Corporation stock is publicly traded on the American Stock Exchange under the symbol "TIV" in the United States and is also traded in Europe on the Frankfurt Stock Exchange under the symbol "TVC WKN 911919." Our company websites, which include all SEC filings, are www.tri-valleycorp.com and www.tri-valley.de.

This press release contains forward-looking statements that involve risks and uncertainties. Actual results, events and performance could vary materially from those contemplated by these forward-looking statements which includes such words and phrases as exploratory, wildcat, prospect, speculates, unproved, prospective, very large, expect, potential, etc. Among the factors that could cause actual results, events and performance to differ materially are risks and uncertainties discussed in the company's quarterly report on Form 10-Q for the quarter ended March 31, 2005, and the annual report on Form 10-K for the year ended December 31, 2004.

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