In quartz veins near the marble contact mimetite occurs as elongated lemon-yellow prisms (to 1.5 mm) which grade into vanadinite. In one area crystalline mimetite forms radiating aggregates of yellow acicular crystals (0.2 X 0.15 mm) that protrude from fracture surfaces in gray limestone in the ceiling of the slope.
Locally it has been found as dark brown botryoidal coatings to 2 mm thick and as individual brown spheres (to 1 mm) associated with dark reddish brown vanadinite. Evidence of multiple episodes of growth is relatively common.
At the Brown Monster mine, vanadinite occurs as transparent reddish brown crystals (to 2 mm) associated with mottramite and wulfenite.
Since 1952 the site has stood abandoned, visited only (and that very infrequently) by mineral collectors searching for vanadinite and wulfenite crystal specimens.
The fame of the Apex mine among mineral collectors rests on two species, vanadinite and wulfenite, which have been found as beautifully crystallized specimens.
The most commonly marketed San Carlos species by far has always been vanadinite: a typical notice, placed in Rocks & Minerals by the dealer Hugh Ford in 1952, offers "Vanadinite, San Carlos, Mexico.
The first specimens found in 2002 range in color from bright red (at first assumed to be vanadinite) to orange, yellow and brownish green (thought perhaps to be pyromorphite); some crystals are elongated, tapered, and bi-colored orange-red and yellow.
The exposed terminations tend to be perfect, whereas the end attached to matrix tends to taper down irregularly, as is often seen with large vanadinite crystals.
Some crystals show reflective, silky zones just below the prism surfaces indicative of micro-voids, exactly as seen on some large vanadinite crystals from Morocco.
There were displays of thumbnail-size calcite twins (Gene and Doris Wright); beautiful agate slabs (Norm and Roz Pellman); glowing, very large specimens of Swiss smoky quartz and pink fluorite (Siber & Siber): a huge case of amethyst specimens of all descriptions and sizes, plus faceted amethyst gems (Bill Larson); rock-forming minerals (but superb specimens of them--Jesse Fisher and Joan Kureczka); minerals of Mexico (Peter Megaw); Arizona vanadinite (Evan Jones); Hallelujah Junction, Nevada quartz (Krystal Tips Mining); general quartz (Bill Severance); worldwide fluorites (Steve Smale); American minerals (the Mineralogical Association of Dallas); highlights of the Lidstrom Family Collection, in memory of the late Walt Lidstrom ...
This year, besides the usual azurites, anglesites, vanadinites, proustites, acanthites, etc.
Matlockites, Suzannites, Leadhillites, Lanarkites, Caledonites, Chromo-phosphates [chromian pyromorphite], Pyromorphites, Kampylites, Vanadinites
, Wulfenites, and Linarites.