Sandstone slab, large Prehnite The heavy dark matrix is

The heavy dark matrix is likely manganese-based

Epidote grows long slender prismatic crystals with saturated olive green color

" Thick lava-like ropy banding create the raised cup of chalcedony with a hollow interior

" this type of calcite from the famed Santa Eulalia mining district grows in hedgehog clusters of sharp dogtooth (scalenohedral) crystals

Locale: Boekenhouthoek

Sandstone slab, large Prehnite The heavy dark matrix isApprox size: 9 1 8 x 6 1 4" (12mm thick) Approx weight: 962g (2lb) The display side of the slab is polished; the reverse is unfinished and may have saw marks, uneven parts, or paler color. This flat polished slab of picture sandstone is made from Arizona Sierra sandstone sourced from central Arizona. Sandstone is a sedimentary rock composed of sand compacted and cemented together through geological processes, giving it a grainy texture. Sandstone with