Sauconite is a complex

phyllosilicate mineral Silicate minerals are rock-forming minerals made up of silicate groups. They are the largest and most important class of minerals and make up approximately 90 percent of Earth's crust. In mineralogy, silica (silicon dioxide, ) is usually consid ...

of the smectite clay group, formula Na_0.3 Zn₃( Si Al)₄ O₁₀(O H)₂·4 H₂O. It forms soft earthy bluish white to red-brown monoclinic crystals typically massive to micaceous in habit. It has a Mohs hardness of 1 to 2 and a specific gravity of 2.45. Optically it is biaxial positive with refractive index values of n_α = 1.550 - 1.580, n_β = 1.590 - 1.620 and n_γ = 1.590 - 1.620. It is found in vugs and seams in the oxidized zones of zinc and copper deposits. It occurs in association with hemimorphite, smithsonite, chrysocolla,

coronadite Coronadite is a black monoclinic mineral containing a ternary oxide of lead and manganese in two oxidation states. The mineral was named after Francisco Vasquez de Coronado Francisco is the Spanish and Portuguese form of the masculine given name ...

and various

iron oxide Iron oxides are chemical compounds composed of iron and oxygen. Several iron oxides are recognized. All are black magnetic solids. Often they are non-stoichiometric. Oxyhydroxides are a related class of compounds, perhaps the best known of whic ...

s. It was named for the Saucon Valley in Pennsylvania, where it was originally discovered in 1875.

References

Smectite group Sodium minerals Zinc minerals Aluminium minerals Monoclinic minerals Minerals in space group 12 Minerals described in 1875 {{silicate-mineral-stub