8 kg RDX
from RDX article, wikipedia:
“RDX is believed to have been used in many bomb plots including terrorist plots. It was said to have been used in the Bombay (Mumbai) serial bomb blasts of 12 March 1993 in which more than 300 people were killed and about 1,500 injured. Again, on 11 July 2006, a series of powerful explosions took place on seven suburban railway trains on Mumbai’s Western Railway line killing 209 and injuring over 700. The use of RDX by the Islamic terrorist outfit Lashkar-e-Toiba in this incident was subsequently confirmed by India’s state investigating agencies. It was recently used in the serial Jaipur blasts, as well as in the Islamabad Marriott Hotel bomb blast of 20th September 2008 in which more than 50 people were killed and more than 300 people were injured.