group corresponding to the secondary unit C4-C4-T1 was represented by the following zeolites stellerite, stilbite, stellerite-Na and stilbite-Ca.
Shortly thereafter, the group found a large zone rich in minerals including laumontite, stilbite, quartz, heulandite
and (the most spectacular of them all) calcite.
There does not appear to be any evidence in the literature to support the presence of variable charge on heulandite
(Ming and Mumpton 1989) or quartz (Drees et al.
Les matieres predominantes remplissant let vacuoles dans Ic basalte sont Ia caladonite et la silice, en compagnie de petites quantites d'<< heulandite
>>, de chabasite et d'analcime.
However, a very small number are lined with attractive combinations of stilbite, heulandite
, albite and calcite crystals.
Some "flowers" came out loose; others have small crystals of heulandite
, stilbite, analcime or calcite attached to their bases.
The common zeolites, including heulandite
and stilbite, are calcium-dominated minerals that are fairly high in silica.
Finely acicular crystals on tanzanite and heulandite
have also been identified (by X-ray diffraction; courtesy of Mike Keim).
Rocko Rosenblatt of Rocko Minerals & Jewelry (email@example.com) had a flat of unusual-looking heulandite
specimens, between 2.5 and 5 cm, from the Fanwood (or Weldon) quarry near Fanwood, Watchung, New Jersey.
GEOdyssey LLC (www.geodyssey-rocks.com) offered excellent miniature and small cabinet-size specimens of fluorite from Naica, Mexico; celestine from Madagascar; and heulandite
and mordenite from the Rat's Nest claim, Idaho; as well as delicate, dazzling thumbnails of pale blue and pale yellow barite from Huarihuayin, Huanuco, Peru--all for $75 to $100.
is now either heulandite-Ca, heulandite-K, heulandite-Na or heulandite-Sr, depending on what metallic element dominates the structure.
Here for instance were 25-cm clusters of transparent golden barite crystals from the Vignola mine; large cabinet-size specimens of the famous red heulandite
on black carbonaceous shale, from Val di Fassa; and, from the same rich valley, surprising specimens on which sharp, bright, pinkish orange crystals of anorthite to 1.5 cm are strewn over matrix.
The specimen shown here has superb aesthetics, with a large and a small cluster perched on a heulandite
Commonly they form fan-shaped aggregates reminiscent of heulandite
. In some cases erythrite forms beautiful acicular crystals to 1 cm long and 1 mm thick--as in the finds of early 2001 and 2005 in the oxidation zone of Vein 7.
Commonly the geodes contain heulandite
and quartz, and rarely also mordenite, stilbite and calcite.