paystreak
The zone, parallel to the walls of a vein, in which the ore is concentrated, or any narrow streak of paying ore in less valuable material.
paystreak: the richest thread running through a vein
A paystreak is a narrow band of economically valuable ore that runs through a larger vein or deposit, often parallel to the vein walls. It is the concentrated zone where metal content justifies extraction; the surrounding rock may be barren or so low-grade that mining it alone would lose money. The paystreak is what transforms a geological feature into a working mine.
In hard rock mining, a vein may be several meters wide but contain paystreak only centimeters thick. A gold-bearing quartz vein, for example, might run 3 meters across a slope, but only a 15 to 40 centimeter band holds enough gold to be milled profitably at current prices. Miners stope selectively, extracting the paystreak and leaving barren wall rock in place to save labor and haulage cost. In placer mining, a paystreak is a thread of coarse gold or heavy minerals concentrated by ancient water flow along a streambed.
Thickness, grade, and the economics of boundaries
The definition of a paystreak shifts with commodity price, milling costs, and strip ratio. When gold trades at 1900 per ounce, a vein of 3 grams per tonne may be paystreak; at 1200 per ounce, the cutoff moves up to 5 grams per tonne. Modern assay drill holes and channel sampling map the paystreak boundaries, but the margins are never sharp. Grade tapers into wall rock, forcing the miner to decide where to cut each round. Selective mining leaves dilution; wide cutting captures all ore but increases waste tonnage sent to the mill.
The paystreak often follows structural features: a pressure-solution seam, a fault zone, a contact between lithologies. Gold may be concentrated in a narrow band of silica-carbonate alteration flanking the main vein. Sulfide ores such as copper and zinc sometimes show paystreaks of higher-grade sulfide minerals separated by bands of quartz or lower-sulfide wall rock. Recognition of paystreak geometry underground guides both mine planning and real-time extraction decisions.
The term is oldest in hard rock and placer mining but applies wherever ore concentration is patchy. It reflects the historical reality that most veins contain both treasure and waste in spatial proximity, and profitable mining depends on finding and following the paying zone. Distinguishing paystreak from surrounding material by eye, feel, or rapid assay remains a core skill on underground mining crews.