Native Silver – Part I

This is the first of two Blogs on native silver. In the first I will introduce the mineral, including a gallery of specimens, and in the following blog, “Ancient Silver Jewelry” I’ll present examples of ancient silver jewelry, coinage, and art works, which demonstrate the innovative artisanship of early silversmiths from varied locations around the world.

Among the native elements, silver, [Ref 1], is a favorite among mineral collectors, as it is for me. Silver offers variations in color from metallic silver-white to the optical interference colors of a thin coating film, (such as on copper sulfide minerals – see my earlier Copper Blog), to the sooty black of a thick coating. From locations around the world it occurs in a number of aesthetic and geometrically interesting forms, ranging from groupings of single crystals (Figures 1-2), spectacular fern-like dendritic arrays of crystals (Figures 3 & 4), and striking wire and sheet forms (Figure 5 & 6). The relative arrangement of crystals in, and the shape of, the dendrites has been found to depend on the conditions of the surrounding silver-bearing solution during deposition of the silver, [Ref 2]. Specimens of wires attached to the silver sulfide acanthite, (Ag2S), grow on oxidation of the sulfide mineral, which liberates the silver, as described below, both by roasting, [Ref 3], or by chemical reactions in solutions within both the oxidized and replacement zones of an ore body, (Slide 9 of [Ref 4]). The wires grow at the interface between the acanthite and silver by continuing the face centered cubic lattice shared by both the acanthite and the silver, [Ref 1]. The sulfur of the acanthite occupies the interstices between the silver atoms. X-Ray diffraction and microscopy have demonstrated the crystallinity of a native silver wire.

In order to share with you these beautiful and intriguing forms of native silver, I’ve included a comprehensive gallery of these forms from around the world, (Figures 3-17). I’ve also taken the liberty of including a favorite specimen from my silver collection in the gallery, (Figure 10).

Because the lore of lost precious metal mines, particularly those in Arizona, New Mexico, and Nevada fascinate many of us; I’ll begin referencing descriptions and histories of these mines and provide brief excerpts from the references. In this blog, the emphasis will be on lost silver mines and in future blogs on silver minerals. Future blogs on Gold and Gold minerals will also include lore & history of lost Gold mines.

Silver Crystal Forms

Silver belongs to the isometric crystal system, [Ref 1], and crystallizes in cubic and octahedral forms as shown in Figures 1 and 2. The forms reflect the symmetry of the isometric crystal system. Silver crystals form twins on the octahedral surfaces of two crystals resulting in a Spinel-Twin, [Ref 6], with the remainders of each of the octahedrons visible, as seen in Figure 3.

Figure 1. Silver crystal in octahedral form, [Ref 1]
Figure 2. Silver crystal in cubic form,  [Ref 1]
 

 

 

 

 

 

 

 

Figure 3. Twinned silver octahedrons, a Spinel-Twin, [Ref 1, 7]

GALLERY OF NATIVE SILVER SPECIMENS

Figure 4. Cubic crystals of native silver on calcite, Kongsberg silver mining district, Buskerud, Norway.
Figure 5. Dendritic silver comprising an array of branches twinned on octahedral faces (Spinel twins, [Ref 3]), Batopilas, Andre del Rio District, Mun. de Batopilas, Chihuahua, Mexico.
Figure 6. Dendritic silver in quartz, comprising arrays of silver crystals twinned on octahedral faces (Spinel-Twins), Creede District, Mineral County, Colorado.
Figure 7. Dendritic silver on native arsenic. Pohla Mine Group, Freiberg, Saxony, Germany. The dendrites feature growth of branches from cubic faces to give mutually perpendicular orientation with respect to the central branch, instead of from octahedral faces as in Figure 4.

 

 

 

 

 

 

 

 

 

 

 

 

 

Figure 8. Dendritic silver in calcite, “The Road Runner” Batopilas, Andre del Rio District, Mun. de Batopilas, Chihuahua, Mexico.
Figure 9. Wire silver growing from acanthite, Reyes mine, Gunaajuato, Mexico. Note the close relationship between the base of the rams-horn-shaped silver wire and its host acanthite crystal.

 

 

 

 

 

 

Figure 10. Wire silver growing from acanthite crystals, Linquiu, Shanxi Province, China. Note the intimate contact between the acanthite crystal and the silver wire.

 

 

 

 

 

 

 

 

 

Figure 11. Wire silver, Himmelsfurst Mine, Brand-Erbisdorf, Freiberg District, Saxony, Germany.
Figure 12. Silver wire with acanthite in calcite, Kongsberg silver mining district, Buskerud, Norway.
Figure 13. Native silver crystals with native copper crystals, White Pine Mine, Ontonagon County, Michigan. An interesting association found at this locality.

 

 

 

 

 

 

 

 

 

 

Figure 14. Distorted cubic silver crystals on copper. Wolverine Mine, Houghton County, Michigan.

 

 

 

 

 

 

 

 

 

 

 

 

Figure 15. Sheet silver, Morenci Mine, Copper Mountain District, Shannon Mountains, Greenlee County, Arizona. The sheet-like form arises from crystallization of small crystals in a closely confined space.

LOST SILVER MINES

The location of the Lost Duppa Silver Mine in Arizona, [Ref 8], lies in the numerous mines and ore deposits of the heavily mineralized Bradshaw Mountains, (Figures 11-16). When discovered, the deposit was a ledge of silver-bearing quartz located in one of the many steep canyons located on the east side, of the northern Bradshaw Mountains. The ore was native silver. After his initial find, Duppa failed to relocate his original path to the deposit and never found it again.

Figure 16. Bradshaw Mountains as viewed from Cow Creek Road, an access road to the mountains, [Ref 9].
Figure 17. The Tip Top Mine, Bradshaw Mountains, [Ref 10].
 

 

 

 

 

 

 

 

 

The Lost Silver Lode of Carbonate Creek, New Mexico, [Ref 11]

The discovery of lode was in the Kingston Mining District, located in the southern region of the Black Range in Southwestern New Mexico. Located within the range are the Chloride, Kingston, and Hermosa Silver Distracts which have been rich producers of the metal. The lost lode lies in the Kingston Silver Mining District shown in [Ref 12], which eventually produced silver amounting to over Six Million in USD. The lost lode was discovered along Carbonate Creek near the town of Kingston as surface float of acanthite (silver sulfide). The weights of pieces of the float ranged up to 250 pounds. Ultimately float yielding over 80,000 ounces was found, but the source of the float was never discovered.

 

 

 

 

 

 

 

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