Siderite is a very common mineral, in lustrous or iridescent deep brown forms, rarely in paler brown translucent balls. Generally it is in sheaf-like bundles, occasionally in ‘bow-ties’. It does occur in rhombs, often with curved multiple surfaces, and these are frequently hollow, with maybe a chabazite or two inside....
Black magnetite octahedra, some with traces of chlorite on their faces, some of which are stepped. Some magnetite crystals are completely encased in chlorite. Blocky orthoclase crystals form part of the cavity lining. Brown sheaf or club-shaped siderite, yellow hexagonal chabazite-Na, and needles of apatite coated with chlorite. Below: Magnetite,...
Gypsum tends to usually occur alone or with barite, chabazite-Na and analcime in the more weathered rock. It forms sprays of clear needles, or larger flat crystals. Below: Gypsum, siderite and chlorite, Bickers Quarry (Simpkins Quarry), Tokatoka, Kaipara District, Northland Region, North Island, New Zealand. Width of view 6mm.
Apatite occurs as fine needles, often coated with brown chlorite. Occasionally it is strung with tiny “herschelite” (chabazite-Na) crystals. Below: Prismatic coated apatite crystal with yellow hexagonal chabazite-Na and orange chlorite. Width of view 6mm.
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...
