argentite

MBRC-1 Spherical [41] Plectonema boryanum Cubic and octahedral [42, 43] UTEX 485 Platelet Pseudomonas aeruginosa -- [44] Pseudomonas aeruginosa Crystalline and [12,14] needle-like Pseudomonas fluorescens Spherical [45] Pseudomonas putida Spherical [46] NCIM 2650 Pseudomonas Hexagonal, [47] stutzeri AG259 equilateral triangle, crystalline silver, and monoclinic silver sulfide acanthite Rhodobacter sphaeroides Spherical [48] Rhodopseudomonas capsulata Nanoplate and [15, 49] spherical Rhodopseudomonas palustris Crystalline, [50] face-centered cubic Serratia nematodiphila spherical, and [51] crystalline Shewanella algae elemental [52] Shewanella algae -- [28] strain BRY Shewanella putrefaciens Fine-grained [53] (Gs-15) crystal Thermoanaerobacter Octahedral [13, 54] ethanolicus TOR-39

Analysis of the diffraction patterns of samples treated in the AgN[O.sub.3] solution showed that some peaks could be indexed to acanthite and silver-3 C.

Acanthite on Calcite La Sirena Mine, Guanajuato, Mexico 4" tall

Daniel showed me some mind-bendingly fine specimens of acanthite and wire silver which have just come from the Hongda mine, Linqqiu County, Datong Prefecture, Shanxi Province: sharp, lustrous metallic gray acanthite crystals to 2 cm form stately stacks to 7 cm, and wonderful thick silver wires rise from matrix of massive acanthite; this matrix is adorned, in a few cases, by gemmy 1.5-cm sphalerite crystals.

One good gape at the "rabbit ears" matrix aquamarine from Mount Antero, the huge leaf gold from the Wapiti mine group, three fabulous Sweet Home mine rhodochrosites, and the Bulldog mine wire silver specimen (an upward-striving nest of curved wires on a 6.5-cm matrix of quartz and acanthite), sufficed to send gawkers down the long rows of other display cases in properly receptive moods.

These chloride ores were called pacos in Peru and colorados in Mexico, while the black sulfide ore below (acanthite) was everywhere called negrillos.

In the first decade of the 20th century, the Las Chispas mine near Arizpe in Sonora produced some of Mexico's largest and best specimens of polybasite crystals, large clusters of "poker chip" stephanite crystals, fine acanthite crystal clusters and a few very fine pyrargyrite specimens.

Since the turn of the century, fantastic specimens of wulfenite, calcite, amethyst, pyrargyrite, acanthite, galena, gypsum--the list goes on and on--have made their way to collections across the globe.

The history of Guanajuato can be traced to a group of Spanish mule skinners who found silver there in 1548, Mining began in 1558 at the San Juan de Rayas mine, which since then has produced large numbers of superb specimens of acanthite, polybasite and other silver minerals.

The locality is the Uchucchacua mine, Oyon Province, Lima Department, already famous for its acanthite, silver, proustite and "arsenpolybasite" specimens.

Black acanthite pseudomorphs after thick native silver wires to about 1 cm long rise from calcite druses, together with small crystals of acanthite paramorphous after argentite.

And the wire silver from the Imiter mine, Morocco is getting fairly amazing, with thin, bright, metallic white wires rising in attractive entanglements to many centimeters tall, on a matrix of dull gray massive acanthite. Now, precisely because of the brightness, tin-whiteness, and thinness of these silver wires, and because of the acanthite matrix, some people inevitably have been thinking about the fake silver specimens Don Edwards once made by roasting acanthite in his kitchen.

Here also were some promising azurite specimens from "Azila," a new Moroccan locality, and five spiky, lustrous thumbnails of acanthite from the Imiter mine.

They're all here, in multiple samples ranging in quality from "study grade" to absolutely superb: Freiberg acanthite and stephanite, Schneeberg proustite and erythrite and roselite and uranium-bearing species, Andreasberg pyrargyrite and dyscrasite and fluorite and pink apophyllite, Siegerland malachite and anglesite and millerite and galena, Schwarzwald fluorite and barite and silver, Obermoschel cinnabar and moschellandsbergite, Ems pyromorphite and cerussite, Johanngeorgenstadt mimetite, Ohrenstock hausmannite, Fichtelgebirge topaz and microcline and herderite, Ehrenfriedersdorf cassiterite and fluorapatite, Ilfeld manganite, Ronneburg whewellite, Hagendorf phosphates ...

Among the few old-time specimens circulating at the show, a remarkable acanthite from the Baccu Arrodas mine, Sarrabus, Sardinia changed hands quickly and is now owned by collector Gian Mario Motta.