Gold Mining Terms In Common Use
1. A “lode” is a highly localized zone of concentration of gold in rock.
2. Mining for gold in rock underground (by tunneling) or in rock exposed at the surface, is called “hardrock mining”.
3. Gold which is found in stream sediments (alluvium) is called “placer”, Spanish for “pleasure”. Digging it is almost always pleasurable compared to the miserable work of hardrock mining. Until methods for working dry placer were developed, “placer” was synonymous with what we now call “wet placer”. The availability of fresh water made the hard work under the hot sun more tolerable.
4. “Wet placer” is placer in or near water, such that it can be worked by panning, sluicing, and other hydraulic methods.
5. “Dry placer” is placer where there is no water. Sometimes such placer is worked by hydraulic methods, using water hauled to the site.
6. “Desert placer” generally refers to dry placer deposited in desert alluvial fans and bajadas. It may be far from any present-day stream channels.
7. A “paystreak” is a zone (typically narrow) in a placer deposit where gold is concentrated.
8. A “mother lode” is a lode large and rich enough to have resulted in the formation of mineable placer deposits.
9. The “Mother Lode” (capitalized) is a regional alignment of geologically related lodes, tens or hundreds of kilometers in length, which has resulted in formation of placer deposits of large extant many of which cannot be identified as having any specific lode as their source.
10. Gold which is gradually being carried downslope from a vein source by erosion and soil creep is often called “eluvial gold”. I prefer to use the phrase “hillslope gold”, since the geological processes are called “hillslope processes” in scientific geology.
11. The phrase “eluvial gold” most properly refers to gold which is being concentrated in place by geological processes such as wind and water erosion which remove lighter material.
12. A “pediment” is a relatively broad and flat upland which is very slowly being lowered by erosion. In most regions a pediment is characterized by soils of limited depth overlying bedrock. However in desert regions pediments are often alluvial fans and bajadas the source streams of which no longer exist. “Bedrock” may be thousands of feet (a kilometer or more) below the accumulated flash flood sands and gravels.
13. “Artisanal mining” is labor-intensive small-scale mining which requires low capital investment and does not rely on sophisticated knowledge of geology. It extracts only a small percentage of the total gold resource at that site. Searching for gold with a metal detector is a form of artisanal mining that didn’t exist (as a practical matter) until the advent of VLF metal detectors forty years ago.
14. “Industrial mining” is large-scale mining requiring large capital investment and the use of heavy machinery. Industrial mining operations are based on sophisticated geological research and are efficient at extracting most of the gold from the site. Such operations are usually large underground mining complexes or large open-pit mines.