Prehnite - Merelani Hills, Lelatema Mts, Manyara, Tanzania
View Larger Chalcedony - Mamuju Area, Sulawesi Barat Province, Sulawesi Island, Indonesia
(Source: e-rocks.com)
View Larger Fluorite, Limonite
CaF2, (Fe,O,OH,H2O)
Locality:
Clara Mine, Rankach valley, Oberwolfach, Wolfach, Black Forest, Baden-Württemberg, Germany
Field of view: 1 mm
Fluorite on limonite.
Photo by Karlheinz Grosch
Fluorite is a very popular mineral, and it naturally occurs in all colors of the spectrum. It is one of the most varied colored minerals in the mineral kingdom, and the colors may be very intense and almost electric. Pure Fluorite is colorless; the color variations are caused by various impurities. Some colors are deeply colored, and are especially pretty in large well-formed crystals, which Fluorite often forms.
Limonite is scientifically not considered a true mineral as it lacks a definitive chemical formula and crystal structure. However, all mineral reference guides list it together with other minerals. Limonite is a matrix base of many other minerals, and the term gossan is used as a reference to Limonite when it is used as a a matrix for another mineral or has formed an undesirable staining on top of it.
View Larger Chalcopyrite, Sphalerite
Cu1+Fe3+S2, ZnS
Locality:
Image width approx. 3.5 mm
Photo by Michael Pfeil
View Larger Vanadinite
Pb5(VO4)3Cl
Locality:
Apache Mine, Radium, Burch area, Globe Hills, Globe Hills District, Globe-Miami District, Gila Co., Arizona, USA
Field of view: 5mm
Collection and photo: Stephan Wolfsried
Fluorite and Quartz - Blanchard Mine, Bingham, New Mexico
(Source: spiriferminerals.com)