The matrix, when present, is stibnite; associated species include valentinite, senarmontite
in sharp crystals to 5 mm, and, very rarely, spherical aggregates of paakkonenite to 1 mm.
Secondary senarmontite occurs with cervantite (Ruzbacka, 1968).
Senarmontite is a product of hypergene alteration of stibnite and native antimony, occurring along the margins of these minerals (Andras et al., 1993b).
Senarmontite occurs rather abundantly in some of the cavities in the quartz-stibnite-antimony veins, where it forms colorless-to-gray transparent octahedrons that average a millimeter across.
The crystals are generally less than 0.5 mm across, and are associated with stibnite, quartz and granular brown microcrystals of senarmontite in cavities in quartz.
The most commonly associated species are quartz, stibnite, native antimony, kermesite and senarmontite. The valentinite is always well-crystallized, and is most commonly white or grayish white, though some of the larger crystals may appear beige to caramel-yellow, or rarely even red due to associated metastibnite.
In the quartz-stibnite-antimony veins, quartz was the first mineral to crystallize, followed in succession by berthierite, stibnite, native antimony, a second generation of stibnite, kermesite, valentinite (+ minor senarmontite), chlorite and senarmontite.
A progressive increase in oxidizing conditions is confirmed by the sequential increase in the valence of antimony, from 0 in native antimony to 3+ in stibnite, kermesite, valentinite and senarmontite, to 5+ in the stibiconite.