Hokonui Formation Agglomerates
Grid Ref (WGS84 Lat/Long in decimal degrees)
Narrow, fine-grained pyroclastic layers show graded bedding and flame structures.
These give way to a thick sequence of agglomerates with the dominant clasts having a similar composition to the matrix. In thin section the clasts consist of albite phenocrysts set in a dirty saussuritic groundmass containing feldspar microlites and minute quartz grains. The clast margins are very fine-grained and almost opaque except for random feldspar microlites.
The matrix to the clasts consists of cryptocrystalline volcanic fragments, blebs of chlorite, coarse clinozoisite and some anhedral feldspar megacrysts. A single ironstone clast was noted from these