Crystal symmetry and chemical composition of yukonite: TEM study of specimens collected from Nalychevskie hot springs, Kamchatka, Russia and from Venus Mine, Yukon Territory, Canada

Abstract

Yukonite, a rare arsenic-bearing hydrous mineral, the crystal symmetry and variety in chemical composition of which have so far been insufficiently studied, has been found in the modern deposit of Nalychevskie hot springs in Central Kamchatka, Russia. This is the first finding of yukonite in Eastern Eurasia and Siberia. Yukonite specimens from Nalychevskie hot springs and from Venus Mine in Yukon Territory, Canada, have been investigated using an analytical transmission electron microscope (TEM). Yukonite is a crystalline substance with extremely thin (∼5 nm) platy morphology. Yukonite from Venus Mine forms brittle aggregates in which grains are irregularly bent and randomly distributed. At Nalychevskie hot springs, yukonite occurs as single plates, coexisting with some amorphous material of similar composition. Intensity distributions in electron diffraction indicate that most plates of yukonite at Nalychevskie hot springs have orthorhombic symmetry, but some are hexagonal with ahex = 11.3 Å. The orthorhombic cell is C-centred with aorth = √3ahex, borth= ahex. High-resolution images of edge-on mounts indicate that the periodicity normal to the planes is d001=11.2 Å. Yukonite from Nalychevskie hot springs contains anomalously high Si relative to that in yukonite from Venus Mine and that reported previously. Strong negative correlation between As and Si indicates that Si substitutes for As in the structure.

Yukonite and wallkilldellite–(Fe) from the Kiura mine, Oita Prefecture, Japan

“…In the results section, new unit cell parameters, a = 11.341(6) Å and c = 11.57(2) Å in a hexagonal cell, were proposed for wallkilldellite-(Fe) from the electron diffraction pattern in TEM observation. When the index of wallkilldellite-(Fe) is applied to yukonite, the unit cell parameters can be written as a = 11.349(6) Å and c = 14.7(2) Å, in good agreement with Nishikawa et al (2006) and Garavelli et al (2010). Comparing the unit cells, yukonite has longer periodicity than wallkilldellite-(Fe) along the c axis, but it is nearly iden- Table 2.…”

“…The chemical composition and X-ray powder diffraction pattern of this type material was later reexamined by Jambor (1966). Yukonite has been reported from several localities other than the type locality (Dunn, 1982;Ross and Post, 1997;Pieczka et al, 1998;Nishikawa et al, 2006;Garavelli et al, 2009). It occurs mostly as a red to yellowish-brown waxy gel-like material or as compact masses of the same color.…”

“…Yukonite has low crystallinity, and its crystal system has long been unknown because only a few weak broad peaks occur in X-ray diffraction (XRD) patterns. However, Nishikawa et al (2006) and Garavelli et al (2009) recently indexed the XRD pattern of yukonite using a hexagonal cell. Another unique property of yukonite is its very wide variation in chemical composition, and various chemical formulae, such as Ca 2 Fe 3+ 3 (AsO 4 ) 3 (OH) 4 ·4H 2 O by Garavelli et al (2009) Ross and Post (1997), have been proposed.…”

Molecular and structural investigation of yukonite (synthetic & natural) and its relation to arseniosiderite

“…Jambor later (1966) re-examined the yukonite formula and proposed the following: Ca 6 Fe 16 (AsO 4 ) 10 (OH) 30 Á 23H 2 O. The occurrence of yukonite since then has been reported among others, in the Sterling Hill mine, Ogdensburg, New Jersey, USA by Dunn (1982), in Saalfeld, Thuringen, Germany by Ross and Post (1997), Redziny, Sudetes, Poland by Pieczka et al (1998), Nishikawa et al (2006) in Kamchatka, Russia and very recently by Garavelli et al (2009) in Grotta della Monaca, Italy. Yukonite has been reported to occur most often as intensively fractured, gel-like aggregates or dark brownish in hand-specimens; in smaller fragments it is purple reddish and slightly translucent.…”

Vibrational Spectroscopy of Complex Synthetic and Industrial Products

“…From this analysis as shown above, it was confirmed that this structure have water molecules, hydroxyl groups that were found to still exist even after heating the sample to > 600 °C (Figure 1). Therefore, based on all this vibrational evidence our preference for a "new"(similar to work by Moore & Ito, 1974) (Tyrrell & Graham, 1913;Jambor 1966;Ross & Post 1997;Pieczka et al, 1998;Paktunc et al, 2003Paktunc et al, , 2004Nishikawa et al, 2006;Becze and Demopoulos 2007;Walker et al, 2009;Garavelli et al, 2009). Finally, in this work it was observed that for arseniosiderite, and additional arsenate IR and Raman active vibrations occurred ~ 900 cm -1 indicative of protonated arsenate groups.…”