Summary: Piemontite-bearing metachert horizons are recorded from regionally metamorphosed eugeosynclinal rocks at Haast River, in the Southern Alps of New Zealand. Piemontite schist mineralogical assemblages produced by epidote-amphibole facies metamorphism are described petro-graphically, and are compared with lower grade occurrences in the Haast Schist Group.

A chemical analysis yields a composition of (Ca_1·75Mg_0·02Mn_0·25Na_0·03K_0·01) (Al_2·23Fe_0·53Mn_0·24 Ti_0·01)Si_3·06O₁₂(OH)_0·9, which is compared graphically with other metamorphic, hydrothermal, and metasomatic piemontites.

Single-crystal Weissenberg and powder camera X-ray data are given, and an attempt made to relate these X-ray parameters to chemical variation within the piemontite composition range.