Goma-2 Eco is a type of high explosive manufactured for industrial use (chiefly mining) by Unión Española de Explosivos S.A. It is a gelatinous, nitroglycerin-based explosive widely used within Spain and exported abroad.
It was used by the Basque terrorist group ETA to mount attacks in the early 1980s. After security was tightened in Spain, ETA switched to obtaining explosives from neighboring France, stealing large quantities of Titadine and using it in numerous car bombings.
The 11 March 2004 Madrid attacks were perpetrated by means of backpacks filled with a total of 120 kg of stolen Goma-2 Eco. A Spaniard, José Emilio Suárez, was subsequently arrested in the northern region of Asturias and was charged with providing explosives for the attacks. Suárez had previously been arrested in 2001 for allegedly stealing explosives from the quarries at Tineo where he worked.