Wulfenite with Calcite

specimen number:
8311095

location:
Hilltop Mine, Cochise Co., Arizona, USA

description:
Platy crystals of wulfenite measuring to 1.2 cm in size across a white crystallized calcite matrix. Some damage present as seen, most of the prominent crystals however are in good condition. Quite nice for this old Arizona classic.

The Hilltop Mine in Cochise County, Arizona, is a historic lead and silver mining locality located in the Chiricahua Mountains. Mining activity began in the late 1800s and worked mineralized veins cutting limestone and other sedimentary rocks. Mining continued only intermittently after that and largely ended by about 1954, so most classic Hilltop wulfenite specimens seen in collections today were recovered from the late 19th century through the 1920s, especially the 1924 to 1927 period. The oxidized zones of the deposit produced a variety of secondary minerals. The mine is especially known among collectors for wulfenite, a lead molybdate mineral that occurs as thin tabular crystals mostly yellow in color. The butterscotch yellow color of wulfenite from the Hilltop Mine in Cochise County, Arizona, is mainly caused by small amounts of trace elements and structural variations within the lead molybdate crystal lattice. Minor substitutions, especially of elements such as chromium or vanadium, can affect how the crystal absorbs and reflects light. These trace impurities, combined with the conditions under which the crystals formed in the oxidized zone of the deposit, produce the distinctive warm yellow to orange yellow color that collectors often describe as butterscotch.

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