galena - teaching student specimens of the primary ore of lead with attached matrix - Talsint (?) Morocco - Unit of 5 specimens In this case it is

In this case it is often considered a cryptocrystalline variety of quartz like chalcedony and is thought of as a mineral

though they show cubic cleavage

a black mechanical pencil (it has an eraser)

The Monastery Beach sand came down a creek

galena - teaching student specimens of the primary ore of lead with attached matrix - Talsint (?) Morocco - Unit of 5 specimens In this case it isGalena PbS Galena is a very common metallic sulfide. It often occurs in cubic crystals and has good cubic cleavage. It is practically the only source of lead, which is used in huge amounts in storage batteries and in shielding from radioactivity. Galena is the Latin name for lead ore. Galena is easily identified by students by its density, metallic luster and its cubic cleavage. Not cleaved into rectangular blocks, though they show cubic cleavage,