Apatite

Hardness: 5 on the Mohs scale. Color: Highly variable, commonly blue, green, yellow, pink, purple, brown, black, or colorless. Due to its vibrant blue-green color, the beads in the image are likely blue or green apatite. Luster: Vitreous to sub-resinous. Crystal Structure: Hexagonal. Cleavage: Indistinct in one direction. Specific Gravity: 3.1-3.2.

Apatite forms in a wide variety of geological environments. It is a common accessory mineral in igneous rocks (e.g., granite, syenite, pegmatite), metamorphic rocks (e.g., marble, gneiss), and sedimentary rocks (e.g., as the primary component of phosphorite deposits). It can also form hydrothermally. Geological age varies greatly depending on the specific formation environment.

Industry: The primary industrial use of apatite is as a source of phosphate for fertilizers (phosphorite is largely composed of apatite). It is also used in the production of phosphoric acid and various chemicals, and sometimes as a minor ingredient in dental products (due to its similarity to enamel). Jewelry: Transparent, well-colored apatite is cut as a gemstone, though its relatively low hardness limits its use to pendants, earrings, and occasional rings that are protected from impact. The beads in the image are likely used for jewelry making.

Apatite is the most common phosphate mineral. It is the mineral that constitutes tooth enamel and bone material in vertebrates. Its name comes from the Greek word 'apatein', meaning 'to deceive', because it was often mistaken for other minerals like beryl, topaz, and tourmaline due to its variable appearance.

In the field, apatite can be identified by its relative softness (easily scratched by a knife), its wide range of colors (especially the distinctive blue-green varieties), and its hexagonal crystal habit when well-formed. It is commonly found in Brazil, Mexico, Canada, the United States (Maine, California), Myanmar, Madagascar, Pakistan, and Russia. For collectors, well-formed crystals and transparent, richly colored gem-quality specimens are highly prized. Identifying its characteristic hardness and crystal form are key. Distinguishing blue apatite from similar-looking minerals like paraiba tourmaline or indicolite (blue tourmaline) can be done by testing its hardness; apatite is much softer.