Labradorite (likely Black Labradorite or Larvikite)

Hardness: 6-6.5 on Mohs scale. Color: Dark gray to black, often with flashes of iridescent blue, green, yellow, or orange (labradorescence). Luster: Vitreous/glassy to pearly. Crystal Structure: Triclinic. Cleavage: Good in two directions, nearly at right angles. Specific Gravity: 2.68-2.72. The beads in the image are dark, suggesting a darker variety of labradorite, possibly referred to as Black Labradorite or even Larvikite (a feldspar-rich intrusive igneous rock composed primarily of labradorite).

Labradorite is a plagioclase feldspar mineral that crystallizes directly from molten magma. It is commonly found in mafic igneous rocks such as basalt, gabbro, and anorthosite. Larvikite specifically is a variety of monzonite or syenite found in the Oslo Graben, Norway. The iridescent play of color (labradorescence) is caused by submicroscopic lamellar intergrowths of two different feldspar types, causing light interference. Geological age varies depending on the specific rock formation it is found in, but many deposits are associated with Proterozoic or Mesozoic igneous activity.

Commonly used as a gemstone in jewelry due to its striking labradorescence, often cut into cabochons, beads (as seen), and carvings. It is also used in decorative architectural applications, especially varieties like Larvikite which are favored for countertops, flooring, and facing stones due to their durability and attractive sheen.

Labradorite was first discovered on Paul's Island near Nain, Labrador, Canada in 1770 by Moravian missionaries, giving it its name. It is sometimes known as 'spectrolite' when it displays a full spectrum of colors, a term often reserved for high-quality Finnish labradorite. In some cultures, it is believed to have mystical properties, such as being a 'stone of magic' or a 'stone of transformation'.

In the field, labradorite is identified by its dark appearance and, most notably, the characteristic iridescent flash of color (labradorescence) when viewed from certain angles. This optical effect is quite unique among common minerals. It's often found in association with other dark, dense rocks. Key locations include Labrador, Canada (original discovery site); Finland (known for spectrolite); Norway (source of Larvikite); Australia, Madagascar, Mexico, Russia, and the USA. When identifying beads, look for varying shades of dark gray to black and rotate them to observe any flashes of color.