Tiger Iron

Hardness: typically 5.5-7 on Mohs scale depending on the layer (hematite vs. quartz/tiger's eye). Color: alternating bands of golden/brown/yellow (tiger's eye), metallic grey/black (hematite), and sometimes red (red jasper). Luster: metallic to silky. Crystal structure: largely microcrystalline quartz and massive hematite.

Formed as banded iron formations during the Precambrian period (often around 2 billion years ago). These are sedimentary deposits consisting of alternating layers of iron oxides (hematite, magnetite) and silica (chert/jasper/quartz). As tectonic and metamorphic forces acted over time, the crocidolite asbestos in the silica layers was replaced by quartz, forming the chatoyant tiger's eye bands.

Primarily cut into cabochons, beads, and carved objects for use in jewelry and decorative items. It is highly valued by lapidary artists for its distinctive banded appearance and contrasting metallic and silky lusters.

Tiger iron is a classic example of a banded iron formation, which are the primary global source of iron ore. The chatoyancy (cat's eye effect) in the tiger's eye layers is what gives it the 'tiger' part of its name.

Identify tiger iron by the distinct alternating bands of metallic grey or black (hematite), golden chatoyant layers (tiger's eye), and sometimes red/brown jasper. It is quite dense due to the high iron content. The major source for commercial tiger iron is the Pilbara region of Western Australia.