Quartz with Hematite (#10)
|Asia||Jinlong, Laolong Ciry, Guangdong Province, China||3" x 2 ¾" x 2 ¼"|
Hematite is iron oxide, Fe2O3. It is a major source (ore) of iron. To be an ore mineral, a mineral must contain one or more elements important to society (iron, copper, zinc, lead, and dozens of others), and it must be economically feasible to extract the element(s) of interest. There are several factors that impact economic feasibility: the mineral must be present in sufficient quantity in the rocks in question; it must be in a form that allows for economical extraction (rather than in a form that is resistant to chemical dissolution or other mining processes); it must be in a location that is accessible; that location must be near enough to water, transportation, and other infrastructure to make mining feasible. In other words, mining companies must be able to make more money than it takes to do the mining. In North America, over 90% of our iron comes from hematite.
Hematite occurs in a variety of forms, from these shiny black plates to rounded redblack lobes to red, formless masses. It all has the same chemical composition, but the environment in which it forms governs its "habit" (the characteristic external form of a mineral). Regardless of its habit or color, all hematite, when powdered, is red. It has been used through the centuries as a red pigment.
The quartz in this specimen is not reddish because of anything inherent in the quartz itself, but because it has been stained by hematite. This may consist of tiny inclusions within the quartz, or on its surface. Note that some of the quartz crystals are colorless.