SIDERITE   HISTORY, NAME, LOCALITIES: Siderite, pronounced SYE-der-ite, has been known since antiquity and was recognized as mineral species in 1845.  Its name stems from the Greek sideros, meaning “iron,” alluding to its composition.  Siderite is abundant and widely distributed with notable collecting localities in Germany, England, Portugal, South Africa, Bolivia, Canada, and the United States (Colorado, Idaho, Arizona, North Carolina, and Connecticut).   MINERALOGY, PROPERTIES, OCCURRENCE: Siderite [iron carbonate, FeCO₃] crystallizes in the trigonal system, usually as rhombohedrons with curved faces; it also occurs in compact, botryoidal, fibrous, granular, and stalactitic forms.  Well-formed crystals are rare.  It is usually translucent and light-to-dark brown in color; occasionally it is reddish-brown.  It has a Mohs hardness of 3.5-4.0, perfect cleavage in three directions to form rhombohedrons, a vitreous-to-dull luster, a conchoidal fracture, and a specific gravity of 3.8-3.9.  Siderite forms in a number of mineralogical environments, including sedimentary deposits, carbonatites, and hydrothermal veins.   METAPHYSICAL PROPERTIES, LORE, USES: The first great iron deposits that fueled the early years of the European and North American iron industries were siderite oolites (granules) that were laid down on seabeds hundreds of millions of years ago.  Siderite is still a minor ore of iron in some regions today.  According to metaphysical lore, siderite is a crystal of positive energy that stimulates the development of constructive thoughts and ideas, while reinforcing interest and enthusiasm about careers and other works.   COLLECTORS’ INFORMATION: Siderite crystals are collected for their rarity and for the unusual curved faces of their rhombohedrons.