This research was carried out to investigate the suitability of locally white sand and Dwaikhla clay (Kaolin) for manufacture of semi-silica refractory bricks as thermal insulators for lining the furnaces. Preliminary investigations had been done to determine the physical, chemical, thermal and mechanical properties with mineralogical constitution of raw materials by XRD analysis. Different amounts of kaolinite were added as binder to the white sand (raw materials) of semi-silica bricks. The specimens molded according to DIN standards by using semi-dry pressing method at pressure of (24.516MPa) according to the DIN1068 standards. After drying process at 110°C the specimens fired at firing temperatures (1000, 1100, 1200, 1300 and 1400) °C. The fired specimens have been investigated to determination the physical properties including bulk density, porosity, and the mechanical properties including compressive strength and thermal properties including thermal conductivity. It has been observed from the results that local white sand and kaolinite could be used as possible source raw materials for manufacture semi-silica refractories, mainly required for glass, ceramics factory in Rammadi.