Bickers Quarry (originally described as Simpkins Quarry) has been owned by Mr. S. Bicker. It is on the north side of Tokatoka Road, a short way east of the junction with Simpkin Road, about 3.5km northeast of Tokatoka (Fig 1 and Fig 2). Tokatoka is about 15km southeast of Dargaville on the North Island of New Zealand.
Tokatoka Peak is a popular tourist location, rising up to about 180m, and is the most prominent remnant plug of a volcano that has been exposed by erosion. It was a relatively small stratovolcano that erupted here about 17 to 19 million years ago in the Early Miocene. Since then the entire volcano has eroded away and erosion has worn down into the rocks that were beneath it.
Bickers quarry is another volcanic plug, composed of augite-andesite, one of many that rose up (Fig. 3) into white Lower Tertiary limestone, which can be seen in the disused adjacent lower quarry. The limestone is responsible for the calcium and barium in the secondary mineralisation in cavities in the andesite. The rock is generally fine-grained and most cavities are less than 10mm, with fractures also coated with crystals. Early reports suggested there were larger cavities with pea-sized analcime found.
Specifically, the rock is part of the Horeke Basalts, which belong to the larger Kerikeri Volcanic Group (Miocene to Pliocene age, roughly 2.5 – 10 million years old). These were subaerial lava flows. Molten basaltic lava flowed across the land surface.
According to Mindat as at 14th August 2025, the mineral list includes: Albite, Analcime, Andradite, Apatite, Aragonite, Barite, Chabazite-Na, Chlorite, Cristobalite, Gonnardite, Gypsum, Harmotome, Hematite, Ilmenite, Laumontite, Magnetite, Natrolite, Orthoclase, Phillipsite, Pyrite, Siderite, Thomsonite-Ca, and Tremolite.
