Tourmaline quartz Lucky bottle

Tourmaline quartz Lucky bottle from China

Tourmaline

Tourmaline is a group of borosilicate minerals with a complex chemical composition and a wide variety of colours. It occurs in virtually every colour of the rainbow, including pink, green, blue, black and multi-coloured combinations. This variety makes tourmaline one of the most popular gemstones in the jewellery world.

Tourmaline usually forms in pegmatites and metamorphic rocks. Major deposits include Brazil, Afghanistan, Mozambique, Nigeria and the United States. The chemical formula varies, but a general form is (Ca,K,Na)(Al,Fe,Li,Mg,Mn)₃(Al,Cr,Fe,V)₆(BO₃)₃(Si,Al,B)₆O₁₈(OH,F)₄. The hardness is between 7 and 7.5 on the Mohs scale.

Popular varieties include black tourmaline (schörl), pink tourmaline (rubellite), green tourmaline (verdelite) and watermelon tourmaline (pink interior, green rim).

Sources:
Mindat.org, Gemdat.org, Wikipedia - Tourmaline

Selenite

Selenite is a clear to translucent variety of the mineral gypsum (CaSO₄-2H₂O). It is known for its glassy to pearly luster and often fibrous structure. A common form is selenite, which has a silky luster and occurs in long, fibrous crystals. Despite its name, selenite has nothing to do with the element selenium; the name is derived from the Greek word for moon, because of its soft luster.

Selenite forms in sedimentary environments during the evaporation of seawater and is found in countries such as Mexico, Morocco, the US and Australia. It is a soft mineral with a hardness of 2 on the Mohs scale, making it easy to work by hand. Almost all selenite sold on the Dutch market is satin spar; however, selenite is a market-accepted sales name.

Sources:
Mindat.org, Gemdat.org, Wikipedia - Selenite