| Silver | |
| Category: | Native metal |
| Formula: | Ag |
| Strunz: | 01.AA.05 |
| Dana: | 1.1.1.3 |
| System: | Cubic |
| Class: | Hexoctahedral (mm) H-M symbol: (4/m 2/m) |
| Symmetry: | Fmm |
| Unit Cell: | a = 4.086 Å; Z = 4 |
| Color: | Silver-white on fresh surfaces; tarnishes to dark grey or black |
| Habit: | As cubes, dodecahedra and tetrahexahedra; rarely as octahedra. Commonly as irregular distortions, twisted wirelike shapes (filiform), arborescent or massive aggregates |
| Twinning: | On common |
| Cleavage: | None |
| Fracture: | Hackly |
| Tenacity: | Highly malleable and ductile |
| Mohs: | 2.5–3 |
| Luster: | Metallic |
| Streak: | Silver-white |
| Gravity: | 10.1–11.1 |
| Melt: | 961.78 °C |
| Diagnostic: | High gravity, silver-white streak, extreme ductility, soluble in nitric acid |
| Solubility: | Soluble in nitric acid |
| Diaphaneity: | Opaque |
| Other: | Highest electrical and thermal conductivity of any metal. |
Native silver is a naturally occurring native element mineral consisting of the chemical element silver (Ag) in its pure metallic form. It is one of the relatively few metals that occur in nature in an uncombined state.[1] It commonly forms distinctive wire-like (filiform), arborescent, dendritic or massive aggregates.
Native silver crystallizes in the cubic crystal system.[2] Well-formed crystals are relatively uncommon and typically occur as cubes, dodecahedra or octahedra. Most specimens exhibit distorted or skeletal growth forms, including twisted wires, capillary shapes, arborescent and dendritic aggregates, herringbone twins and hopper crystals. These habits commonly develop in open cavities within hydrothermal veins, where rapid crystallization under low-temperature conditions favors elongated and branching morphologies rather than euhedral forms.
On freshly exposed surfaces, native silver displays a bright silver-white color and strong metallic luster. Upon exposure to atmospheric conditions, it commonly develops a dark gray to black tarnish due to the formation of silver sulfides, principally acanthite (Ag₂S). The mineral has a Mohs hardness of 2.5–3 and is sectile, easily cut with a steel blade. Specific gravity ranges from 10.1 to 11.1, reflecting its high density. It is extremely malleable and ductile, capable of being hammered into thin sheets or drawn into fine wire. Fracture is hackly and cleavage is absent. The streak is silver-white. Native silver is opaque and exhibits the highest electrical and thermal conductivity of any metal, along with excellent reflectivity across the visible spectrum.
Native silver is soluble in nitric acid, producing silver nitrate solutions, but remains insoluble in hydrochloric acid. It is resistant to most acids under normal conditions but reacts readily with sulfur compounds in the environment, forming secondary silver sulfides such as acanthite. Native silver forms limited solid-solution series with gold (Au) and copper (Cu); compositional variation toward Au-rich members grades into the Au–Ag alloy mineral electrum, while minor copper substitution may occur in solid solution. It may also incorporate small amounts of mercury (Hg), locally forming natural silver amalgams. Antimony (Sb) and bismuth (Bi) are commonly present in associated sulfosalt minerals such as pyrargyrite, proustite and polybasite. In certain hydrothermal systems, silver occurs with tellurium (Te) to form telluride minerals including hessite (Ag₂Te), rather than as native metal.
Native silver forms primarily in low-sulfidation epithermal veins, supergene enrichment zones of silver-bearing deposits and, less commonly, in placer concentrations. It is frequently associated with acanthite, argentite, native gold, native copper, polybasite, proustite, pyrargyrite, stephanite, galena, sphalerite, quartz and calcite.[3] Significant historical and modern occurrences are documented in Kongsberg (Norway), Freiberg (Germany), Imiter (Morocco), Fresnillo, Pachuca-Real del Monte, Batopilas, Taxco (Mexico), Cerro de Pasco, Uchucchacua, Huarón (Peru), Potosí (Cerro Rico), Oruro (Bolivia), Colorado, Nevada, Michigan (United States) and the Cobalt District (Timiskaming District), Thunder Bay District (Canada).
Native silver has been utilized since prehistoric times for ornamental purposes, tools and early coinage due to its natural occurrence, workability and aesthetic appeal.[4] During the colonial period in the Americas and in European mining districts, surface-oxidized veins yielded substantial quantities of native silver in distinctive forms, many of which were subsequently melted for bullion. Well-preserved specimens are now highly valued in mineral collections.
Although native silver constitutes only a minor fraction of global silver production, the metal is extracted predominantly as a by-product of base-metal mining. Annual global mine production of silver was 26,000 tonnes in 2023.[5] [6] Silver’s exceptional electrical and thermal conductivity and reflectivity make it indispensable in electronics (27% of U.S. consumption), photovoltaics (10%), jewelry (6%), catalysis, medical applications, water purification and high-performance mirrors.[7]
Global production of native silver is minor; most silver is derived from sulfide minerals as a by-product. The majority of global supply originates from the mining and processing of lead, zinc and copper ores, particularly from minerals such as galena and sphalerite, in which silver occurs in trace to significant concentrations. Primary silver mines account for a smaller proportion of total output, while recycling of industrial scrap and photographic materials contributes an additional secondary supply stream.
| Native Silver | Ag | 2.5–3 | 10.1–11.1 | Wires, dendrites, arborescent | High (tarnishes easily) | |
| Native Copper | Cu | 2.5–3 | 8.9 | Masses, nuggets, dendrites | Moderate | |
| Native Gold | Au | 2.5–3 | 19.3 | Nuggets, flakes, dendrites | Moderate to high | |
| Native Platinum | Pt | 4–4.5 | 21.5 | Grains, nuggets | Rare |
