Chemical Formula. FeS 2. Iron sulfide. Pale brass-yellow to nearly white. Tarnish es to a dark brass-like brown or with iridescent colors. Dark brown to black, with slightly green tinge. Crystal System. Crystal Forms and Aggregates. Usually as bipyramidal and tabular crystals, commonly in coxcomb aggregates and bladed.
Crystals frequently form curved formations as well as herringbone patterns. Also occurs massive , radiating , mammilary , encrusting , nodular , as groups of small crystals, and in radiating discs known as dollar s. Commonly forms as pseudomorph s over other minerals and fossils, resulting in bizarre shapes and forms. Specific Gravity. Other ID Marks. Tarnish es to a dark brass-like brown. Chemical Composition: Iron Sulfide FeS 2 Mineral Class: Sulfides Crystallization: Orthorhombic Crystal Habit: Commonly well crystallized with tabular forms of crystals most common; also commonly finely crystalline and massive; occasionally found in fossils that have become mineralized; sometimes resembles pyrite, which is much more common in Ohio.
Specific Gravity: 4. Resources Carlson, Ernest H. Pough, Frederick H. Sorrell, Charles A. Type 4 marcasite are short thick prisms with diamond-shaped cross-sections dominated by third order prisms and deeply striated basal pinacoid forms. Finally, type 5 marcasites are square tabular brassy crystals with square cross-sections on the a crystal axis.
Marcasite in these deposits is usually associated with sphalerite, calcite, galena, dolomite and pyrite. Some of the more prominent reported occurrences for marcasite in Grant county are: — In the Platteville district with crystals and masses found in mines in T. Particularly fine crystals reportedly occur in the Rasque ore body in the NW Sec. Habits described for Grant County are also typical of Iowa County.
A few of the more prominent marcasite localities in Iowa County are: — Raasch describes both botryoidal, reniform marcasite and slender stalactitic marcasite several centimeters long from the mines near Mineral Point.
The stalactites have open tubes in the center, and some occasionally curl up the tip, forming helectites. Similar habits are found in Lafayette County, where they are described in more detail.
Associated minerals are galena, goethite pseudomorphs after pyrite, drusy quartz and calcite Heyl et al. All of the localities described under sphalerite and galena for this county are also localities where marcasite is found. The habits described for marcasite in Grant County also occur in Lafayette County. A number of authors Peck, ; Heyl et al. Only a few of the many marcasite occurrences in the county are mentioned below.
Some specific localities given by Heyl et al. Other localities in the township include the Teasdale Mine in Sec. Cordua field notes.
Mine tunnels became coated with colorless to green efflorescences of iron sulfates. Since the alteration of marcasite to these sulfates was exothermic, temperatures in the marcasite rich zones were said to be high enough to cook an egg. Clear Spring Mine in Polk County has been mining marcasite for many years. Starting in Vancouver and traveling down throughout the Washington area, there are several mines set up within the North Cascades National Park.
Over 10 different mines in Northern California can provide you with all that you could ever want. Such mines include:. It is also possible to find some stones that are creamy white and even ones with a rosy brown tint to them. When you are looking for marcasite stones, you will want to find the ones that have the brightest colors. The shape of the marcasite is also very important. Some crystals will take on the appearance of stalactites and stalagmites while others will simply appear geometrical.
0コメント