Formula: Ag2S Monoclinic Description: Acanthite is a low-temperature hydrothermal mineral. It can form from inversion of argentite, a mineral that forms in higher temperature hydrothermal deposits. ONEIDA COUNTY: Acanthite occurs with gold, silver and other silver minerals …
Oneida County
Actinolite
Formula: Ca2(Mg,Fe)5Si8O22(OH)2 Monoclinic Description: Actinolite is a common member of the amphibole family. It typically forms during low-grade metamorphism of mafic igneous rocks (such as basalt and gabbro) or carbonate-rich rocks such as limey mudstones. ASHLAND COUNTY: Van …
Biotite Group
Formula: K(Mg,Fe)3(Al,Fe3+)Si3O10(OH,F)2 Monoclinic Description: Biotite refers to a group of common rock-forming minerals forming a series between phlogopite and annite. The name is best used as a field name for dark micas for which the exact composition …
Chalcopyrite
Formula: CuFeS2 Tetragonal Description: Chalcopyrite is an important ore of copper found in a wide range of hydrothermal environments. It is often associated with sphalerite and galena. It oxidizes to form copper minerals such as malachite, azurite, …
Chlorite Group
Formula: (Al, Fe, Li, Mg, MN, Ni, Zn)6 (Si, Al)4O10(OH, O)2 MONOCLINIC or TRICLINIC Description: Chlorite represents a group of over 10 minerals related by complex solid solution substitutions. These minerals are generally fine-grained, micaceous and dark green. …
Chloritoid
Formula: (Fe,Mg,Mn)Al2(SiO4)O(OH)2 Monoclinic Description: Chloritoid forms small green platy to micaceous grains in rocks that have been subjected to moderate grades of regional metamorphism. It may also form by hydrothermal alteration of rocks. It occurs with muscovite, …
Cummingtonite
Formula: (Mg,Fe)7Si8O22(OH)2 Monoclinic Description: Cummingtonite is a member of the amphibole family. It commonly forms elongated to fibrous green to brown grains in metamorphosed iron-rich rocks. ASHLAND COUNTY: Cummingtonite is found in the Ironwood Iron Formation where it …
Diopside
Formula: CaMgSi2O6 Monoclinic Description: Diopside occurs in moderate to high-grade metamorphic rocks. It is particularly common in marbles, calc-silicate rocks, and amphibolites. FLORENCE COUNTY: Found with tremolite in marble from a drill core into a metasedimentary sequence from …
Dyscrasite
Formula: Ag3Sb Orthorhombic Description:Dyscrasite as a rare mineral found with other silver minerals in hydrothermal deposits.ONEIDA COUNTY: Dyscrasite occurs with silver, gold, pyrargyrite, acanthite, galena, sphalerite and chalcopyrite in the Lynn massive sulfide deposits (Kennedy et …
Epidote
Formula: Ca2(Al2Fe3+)(Si2O7)(SiO4)O(OH)2 Monoclinic Description: Epidote is a common mineral formed during low grades of metamorphism and hydrothermal activity. It is particular common in metamorphosed basalts and gabbros where it replaces plagioclase, pyroxene and olivine. It can also …