The purpose of the current study is to investigate the geopolymeric reactivity of volcanic tuff of Datca Peninsula (Earth of Datca) in Turkey and to evaluate whether it can be used as a green binder. The effects of alkali activator type, alkali hydroxide concentration, activator ratio, and curing conditions on the physical and mechanical properties were investigated. A combination of sodium silicate solution (SS) and potassium hydroxide (KOH) (12.5 M) with an activator ratio of 2.5 is selected as optimum activator type. Sealed curing at 90 degrees C and 90 +/- 5% RH for 24 h provides the highest physical and mechanical properties. Results reveal that "Earth of Datca" as a natural pozzolan is a suitable precursor for the production of a geopolymer material with the properties of 2.0 g/cm(3) bulk density, 5.4% water absorption ratio, 0.64 saturation coefficient, and 10.5 MPa compressive strength. The mortar produced in this research has promising characteristics to be used as a building material.