Physical properties of Gabbro include Color, Streak, Hardness, Structure, Cleavage, Fracture, Luster, Specific Gravity etc. The strength of Gabbro is 225.00 N/mm 2. Streak of Gabbro is black while its cleavage is not available. Luster of Gabbro is not available and its fracture is conchoidal. Gabbro is opaque in nature.