Houston, Texas – Black Stone Minerals Company, L.P., announced it agreed to buy all of the Upper Gulf Coast producing and non-producing mineral and royalty assets and some limited associated working interest properties of Pure Resources Corporation, a wholly owned subsidiary of the UNOCAL Corporation for approximately $192.4 million, effective October 1, 2003.

The properties are located in ten states – Mississippi, Texas, Alabama, Louisiana, Oklahoma, Florida, Arkansas, Pennsylvania, Michigan and New York – and comprise approximately 6.4 million gross acres or 3.2 million net acres. They include royalty and overriding royalty interests in approximately 1,100 wells, with net daily production of approximately 15 million cubic feet per day on a gas equivalent basis. The transaction has been approved by the boards of directors of both companies, and is expected to close in June 2004.

"This acquisition is a major step forward for Black Stone," said President Thomas L. Carter. "We like the Pure Resources minerals for their geographic diversity, solid production base and acreage position. We are also excited to make the extensive unleased mineral acreage holdings available to the industry for exploration and development activities. This acquisition is extremely complementary to our existing portfolio of assets, and continues to provide our investors and limited partners the returns on investment and opportunities for the business plan we have established.”

Black Stone including its institutionally supported partnerships is one of the largest privately owned mineral companies in the United States. Along with its limited partners, Black Stone now owns mineral holdings in approximately 8.5 million net mineral and royalty acres, in virtually every significant onshore exploration basin in the lower 48 states. They possess interests in approximately 15,000 wells, producing in excess of 3.1 million barrels per year on an oil equivalent basis.