Today, one type of acceptable sustainable masonry is to use high percentage of a pozzolan for cement substitution in the masonry grout. Today the typical pozzolan is a waste (or artificial) pozzolan in the form of fly ash and/or ground granulated blast slag. Both of these waste products are trending downward—due in part to alternative energies and recycling of steel. However, the use of high percentage cement replacement as a sustainability practice is trending upward. The conflicting trends put into question the long term viability of waste pozzolans as a sustainable practice (available for future generations). An answer to the question is to turn from waste pozzolans to natural pozzolans—or at least offer a choice. Natural Pozzolans are plentiful and economically available around the world. This paper gives a quick background on origins of pozzolans and reasons for turning toward natural pozzolans in the future. Also, it reports on investigations into the masonry grout specimen strengths of partial percentage cement replacement with a Class N non-calcined clay natural pozzolan. These investigations indicate that 20% and 30% cement replacement can achieve minimum masonry grout strengths, while 40% replacement require further study.