Pyrope, augite, and hornblende from Kakanui, New Zealand

Pyrope, augite, and hornblende occur as xenocrysts in a volcanic breccia of Whaingaroan (Lower Oligocene) age at Kakanui. The pyrope has the composition Py 66·4 Al 20·0 Gr 10·9 An 2·1 Sp 0·6 ; n = 1 · 741; D = 3 · 72; a = 11·536 Å. The augite is an aluminous variety with tschermakitic affinities; α = 1·686, β = 1·691, γ = 1·713; optically positive, 2V = 55°; D = 3·33. The hornblende is a hastingsite; α = 1·676, β = 1·687, γ = 1·695; optically negative, 2V = 80°; D = 3·22. The occurrence and associations of these minerals suggest that they originated in the upper mantle.