Saffordite is a rare form of natural glass with a highly localized origin. While it shares many visual characteristics with true impact glasses, known as tektites, scientific analysis classifies Saffordite as a terrestrial, volcanic glass. This distinction makes its single-source location near the town of Safford, Arizona, compelling for enthusiasts.
Identifying Characteristics of Saffordite
Saffordite specimens are typically small and possess a distinct morphology that causes them to be mistaken for tektites. The exterior of the glass is usually dark, presenting as opaque black or deep brown in natural light. This dark surface is frequently covered in small, shallow depressions, giving it a pitted texture that results from millions of years of chemical etching by acidic water in the soil.
When held up to a strong light source, the true color and translucency of Saffordite are revealed. Translucent specimens display a range of hues, most often appearing as a smoky brown, golden-yellow, or light lavender color. This optical quality is a distinguishing feature, contrasting with the opaque appearance of many other dark volcanic glasses like common obsidian. Chemically, Saffordite is an ancient, weathered form of volcanic obsidian, which is a silica-rich glass that cooled too quickly to form a crystalline structure.
Primary Geographic Source
The entire known distribution of this material is contained within a relatively small area of southeastern Arizona, centered around the town of Safford. This region defines the Saffordite strewn field, which extends over a roughly 100-mile radius. The material is not found uniformly across this area but is instead concentrated within specific geological settings.
Specimens are primarily recovered from the desert floor, having been eroded out of ancient sedimentary layers and transported by water flow. The collection sites often lie within the alluvial fans and washes that drain the region, particularly those associated with the slopes of Mount Graham. The material is found in a secondary context.
The geographical source of the parent rock material is believed to be “upstream” from the main collection areas, with Cow Canyon and Mule Creek being cited as two possible primary volcanic source regions. Collectors typically search in dry stream beds and mesa edges where the glass has been concentrated by millennia of weathering and erosion.
Geological Context of Discovery
The presence of Saffordite in Arizona is directly linked to ancient volcanic activity that occurred approximately 18 million years ago. Unlike true tektites, which are formed by the hypervelocity impact of a meteorite, Saffordite originated from a terrestrial eruption. During this event, molten magma was ejected, rapidly cooling into small glass fragments known as volcanic bombs.
These solidified droplets fell back to Earth as volcanic glass, where they were later incorporated into surrounding sediments. Over vast stretches of time, the fragments were subjected to continuous weathering, tumbling, and abrasion by water and sediment. This natural tumbling process gave the Saffordite its characteristic rounded, sometimes ellipsoidal shape, while chemical action from acidic groundwater created the distinctive surface pitting.
The specimens are typically found on the surface where they have weathered out of the host rock, often in gravel deposits that have been exposed by wind and rain. While the material may resemble the extraterrestrial glass of the North American Tektite Field, Saffordite is geologically distinct, sharing a composition closer to other terrestrial obsidians of the region.