and pickeringite crystallize as post-mining formations in old galleries.
occurs very rarely as a white to pale gray, fine, fibrous, supergene efflorescence on altered pyrite and marcasite, typically associated with other alteration products such as rozenite, sulfur and natrojarosite.
Associated minerals are: coskreaite-(Ce), levinsonite-(Y), melanterite, halotrichite
, picketingite, apjohnite, epsomite and other hydrated sulfates.
Amazingly, Jones and Novak were able to salvage many of the specimens by teasing the halotrichite
hairs up again with a comb and trimming them carefully with scissors.
Silky, white, capillary crystals and fibrous masses of halotrichite
coating surfaces in old workings are relatively common (Panto, 1956).
28Mg[SO.sub4]*7[H.sub.2]O + 20Fe[A1.sub.2][([SO.sub.4]).sub.4]*22[H.sub.2]O + 5[O.sub.2] + 4[Na.sup.+] epsomite halotrichite
in hair salt
Fast-growing fibrous masses of halotrichite
and pickeringite are common in many of the Cerro Rico adits and drifts.
An extremely rare secondary, mineral, halotrichite
has been found in a sulfide-rich cavity in the contact zone as curly, opaque, white fibrous tufts 1-2 mm long on pyrite.
Metavoltine occurs in 0.1-mm lemon-yellow flakey crystals associated with other sulfates including halotrichite
, melanterite, roemerite and voltaire.
They have grown in a pyrite-chlorite matrix with capillary white halotrichite
and fibroferrite (?).
Typical minerals formed under these conditions are water-soluble sulfates such as chalcanthite, melanterite and halotrichite
, along with other more insoluble minerals such as malachite and chrysocolla.
Fe[Al.sub.2][([SO.sub.4]).sub.4] [multiplied by] 22[H.sub.2]O