WHITEITE (EXTREMELY RARE), ARROJADITE, QUARTZ, AZURITE, SIDERITE (miniature)

A group of basic phosphate minerals with the general formula indicated above, where:

A denotes a large divalent cation (Ba, Sr, Pb) plus a vacancy, or two monovalent cations (K, Na),
E denotes a small divalent cation (Fe, Mn, Mg) plus a vacancy, or two Na cations,
M is a small divalent cation (Fe, Mn, Mg), whose identity defines the root-name: Fe, arrojadite, or Mn, dickinsonite, R is a small trivalent cation (Al, Fe) and W is a hydroxide or fluoride ion.

An arrojadite from Yukon contains traces of N (~700 ppm of N) in the form of NH₄⁺ ions.

Siderite is a mineral made up of iron(II) carbonate (FeCO3), deriving its name from the Ancient Greek term σίδηρος (sídēros), which translates to "iron." This mineral is an important source of iron, containing 48% iron while being free of sulfur and phosphorus. Iron can be replaced by elements such as zinc, magnesium, and manganese, leading to the formation of solid solution series like siderite-smithsonite, siderite-magnesite, and siderite-rhodochrosite. 

With a Mohs hardness ranging from 3.75 to 4.25 and a specific gravity of 3.96, siderite exhibits a white streak and displays either a vitreous or pearly luster.

Azurite, also referred to as Azure spar, is a soft, vibrant blue copper mineral formed through the weathering of copper ore deposits. In the early 19th century, it was commonly called chessylite, named after its type locality in Chessy-les-Mines, near Lyon, France. This mineral, characterized by the basic carbonate formula Cu3(CO3)2(OH)2, has a long history, having been noted in ancient texts such as Pliny the Elder's Natural History, where it was identified by the Greek term kuanos, meaning "deep blue," and the Latin term caeruleum. The blue hue of azurite is attributed to the presence of copper ions.