Minerals in space group 221

thumb|upright|Salammoniac crystal from Ravat Village, Tajikistan. One of many unusual salammoniac crystal specimens found in the area of Ravat Village, near [[Yaghnob River, where the crystals have grown in a feather-like or three-dimensional arborescent. Size: miniature, 3.3 × 1.4 × 1.4 cm]]

Awaruite is a naturally occurring alloy of nickel and iron with a composition from Ni2Fe to Ni3Fe.

Boleite is a complex halide mineral with formula: KPb26Ag9Cu24(OH)48Cl62. It was first described in 1891 as an oxychloride mineral. It is an isometric mineral which forms in deep-blue cubes. There are numerous minerals related to boleite, such as pseudoboleite, cumengite, and diaboleite, and these all have the same complex crystal structure. They all contain bright-blue cubic forms and are formed in altered zones of lead and copper deposits, produced during the reaction of chloride bearing solutions with primary sulfide minerals.

Auricupride is a natural alloy that combines copper and gold. Its chemical formula is Cu3Au. The alloy crystallizes in the cubic crystal system in the L12 structure type and occurs as malleable grains or platey masses. It is an opaque yellow with a reddish tint. It has a hardness of 3.5 and a specific gravity of 11.5.

Hapkeite is a mineral discovered in the Dhofar 280 meteorite found in 2000 in Oman on the Arabian Peninsula. The meteorite is believed to originate from the Moon; specifically, it appears to be a fragment of lunar highland breccia. Hapkeite's composition is of silicon and iron, and it is similar to other silicon-iron minerals found on Earth. An impact on the Moon is thought to have launched the partially molten or vaporized material into orbit.

Tausonite is the rare naturally occurring mineral form of strontium titanate: chemical formula: SrTiO3. It occurs as red to orange brown cubic crystals and crystal masses.

Djerfisherite is an alkali copper–iron sulfide mineral and a member of the djerfisherite group.

Skaergaardite is an intermetallic platinum group mineral with the general chemical formula PdCu. The mineral is named after its discovery location: the Skaergaard intrusion, Kangerdlugssuaq area, East Greenland. The mineral name was approved by the International Mineralogical Association in 2003. The mineral has also been reported in the Duluth intrusion in Minnesota and the Rum layered intrusion in Scotland.