The chemical formula of mineral Pyrophyllite is indicated by AlSi2O5OH or Aluminum Silicate Hydroxide. Pyrophyllite is actually a Silicate mineral. Pyrophyllite is used as a refractory mineral, as a filler for rubber, paints and insecticides, as an ornamental stone, as a component of ceramics and as a mineral specimen for which it can be seen exhibiting splendid microscope appearance when viewed under polarized light microscopes used in the field of optical mineralogy. Mineral Pyrophyllite derived its name from the Greek words for fire and leaf as in fire-leaf. Pyrophyllite is also named after the Greek word for leaf as well. This is actually an allusion to its flaky fracture that can be seen more clearly visible when viewed with the aid of petrographic polarizing light microscopes used in optical mineralogy. Pyrophyllite also gets its name from the fact that when water is driven off upon heating it, it exfoliates leaving a flaky mass. It has been found with some studies in optical mineralogy that the flakes are actually the silicate sheets that are a testament to the structure of mineral Pyrophyllite. 

 

            It has been also known in the field of optical mineralogy that Pyrophyllite is an early stage metamorphic mineral and is actually quite common although usually not very abundant as good mineral specimens. Pyrophyllite is also found a constituent of slate, phyllite, some schists and other early stage metamorphic rocks. When evaluated in reflected light of polarized microscopes, phyllites are usually found exhibiting pearly luster that helps giving the pyllites their well known shiny luster. Pyrophyllite is actually a member of the phyllosilicates or the leaf silicates. These silicates have a sheet-like structure, which can be seen more clearly exhibited when viewed under polarizing microscopes used in the fid of optical mineralogy.

 

            It has been known in the field of optical mineralogy that there are two Pyrophyllite minerals. One is found monoclinic while the other one is triclinic. Ordinarily, they would be treated as two distinct minerals but their properties are identical and thery are most often associated and intergrown. Separating them according to mineralogists would serve no purpose that is why for now, they are considered as one. Pyrophyllite is known to be isomorphous with talc. In the field of optical mineralogy, isomorphous means, the two minerals would share the same structure but they certainly have different chemistries. Although Pyrophyllite loses water and exfoliates, in the field of optical mineralogy it has been found to become stable at higher temperatures up to 800 degrees Celsius. This makes Pyrophyllite a valuable as a refractory mineral. Pyrophyllite also seems to be best as a carrier for insecticides and is often the filler of these products.

 

            Although Pyrophyllite is mostly regarded as an ordinary metamorphic mineral, it is still quite interesting and does form some very attractive mineral specimens that would appear more fascinatingly wonderful when viewed with the aid of petrographic polarizing light microscopes for mineralogists. Pyrophyllite with splendid radiating stellar aggregates from Mariposa County California is some of the fascinating and quite appealing specimens showing bright pearly luster and radiating habit. Pyrophyllite is usually found white, colorless, yellow, gray, pale green and/or blue which can be more splendidly exhibited when specimen is viewed under petrographic polarizing microscope used in optical mineralogy. Pyrophyllite can be also stained brown by iron oxides. Mineral Pyrophyllite is most commonly found showing greasy to dull luster when viewed in reflected light of polarized microscopes. However, it can be seen exhibiting pearly luster on cleavage surfaces when specimens are evaluated more closely with the aid of polarizing microscopes used in optical mineralogy.

             Pyrophyllite mineral crystals are most commonly found translucent to opaque in appearance. Pyrophyllite is also known to crystallize in the monoclinic system of crystal formation. In optical mineralogy, the monoclinic system of crystal formation comprises crystals having three axes of unequal lengths. Two of which are usually found in a position that is oblique or not perpendicular to one another. However, both of which are commonly found perpendicular to the third axis. The crystal habit of mineral Pyrophyllite as described in the field of optical mineralogy usually includes typical fine grained, fibrous and lamellar masses, stellate aggregates and radiating spherules all of which are more splendidly exhibited when viewed with the aid of polarized microscopes. Individual crystals of mineral Pyrophyllite are usually rare, but they have a tabular subhedral or distorted form.                 Mineral Pyrophyllite is most commonly found exhibiting perfect cleavage in one direction, which can be seen more clearly visible when specimen is viewed with the aid of petrographic polarizing microscope used in the field of optical mineralogy. Pyrophyllite is also usually found showing uneven or splintery fracture when evaluated under polarized microscopes for mineralogists. The hardness measure of Pyrophyllite when it is evaluated using the Mohs scale method is usually ranging from 1 to 1.5, which is soft enough to be scratched by a fingernail. Pyrophyllite is most commonly found leaving a white streak when specimen is rubbed on a white porcelain streak plate. The specific gravity measure of mineral Pyrophyllite is approximately 2.65 grams per cubic centimeters to 2.85 grams per cubic centimeters, which is average value. Pyrophyllite is usually found showing flexible but inelastic cleavage sheets. It has also a distinctive greasy feel to the touch. The best field indicators of mineral Pyrophyllite usually include color, crystal habit, softness, cleavage, aluminum test and feel. Pyrophyllite is most commonly found associated with micas, chlorite, quartz, graphite, albite, barite, gypsum, andalusite, kyanite, sillimanite, epidote, and lazulite. Mineral Pyrophyllite notably occurs at several localities including Belgium, Mexico, China, Switzerland, Brazil, Sweden, Russia, Japan, Korea and some areas in the United States including North and South Carolina, California, Arizona, and Georgia.