Stone and oil used in the product of asphalt are taxable if the asphalt is used for contracts with the state for highway improvements. In most cases a manufacturing exemption would be applicable since the stone and oil and being produced into asphalt. However, the highway improvements are considered construction projects where materials are being affixed to real property, thus making the taxpayer ineligible to use the manufacturing exemption. (Golden Eagle Construction Company Inc. v. Commonwealth of Pennsylvania, Pennsylvania Commonwealth Court, No. 339 F.R.2000, December 10, 2002)