Endlichite can be an variety that is arsenic-rich of. It forms a solution that is complete between Vanadinite and Mimetite, with increasing quantities of Arsenic replacing Vanadium. Endlichite is just a rare mineral that is secondary through the oxidation of primary lead minerals such as Galena. It precipitates from aqueous solutions in veins and solution cavities, along along with other lead that is secondary.
There are just four locations for finding Endlichite: Erupción Mine (Ahumada Mine; Erupción-Ahumada Mine), Los Lamentos Mts (Sierra de Los Lamentos), Mun. de Ahumada, Chihuahua, Mexico; Ojuela Mine, Mapimí, Mun. de Mapimí, Durango, Mexico; Midelt, Khénifra Province, Meknès-Tafilalet Region, Morocco; Chalk Mountain Mine, Chalk Mountain District, Churchill Co., Nevada,Usa.
|Crystallography:||Hexagonal – Dipyramidal|
|Crystal Habit:||Well developed hexagonal prisms  with smooth faces and sharp edges; commonly cavernous, also acicular, hairlike, fibrous, rounded, globular, skeletalized. Crystals may exhibit concentric zones of varying composition.|
|Hardness (Mohs):||2.5 – 3.0|
|Density:||6.88 (g/cm3); Density decreases with the substitution of Ca for Pb; repaorted values range between ~6.5 to 7.1.|
|Health Warning:||CAUTION: Contains Arsenic – always wash hands after handling. Avoid inhaling dust when handling or breaking. Never lick or ingest.|
|Other:||Readily soluble in HNO3 to a yellow solution; soluble in HCl to a green solution with the deposition of lead chloride.|
|Color:||Orange, Orangish Brown, Brown|
|Transparency:||Translucent to Opaque|
|Luster:||Adamantine to Sub-Adamantine, Resinous|
|Refractive Index:||2.350 – 2.416 Uniaxial ( – )|
|Pleochroism:||Weak; Visible in tinted material in transmitted light; Dichroism: e = light, w = darker|