hade
To slope or incline from the vertical.
hade: when a drill hole or vein leans instead of standing straight
In mining, hade describes the angle at which a borehole, ore vein, or fault plane deviates from vertical. A perfectly vertical hole has zero hade; one tilted at 20 degrees from vertical is said to hade 20 degrees. The term comes from Old English and appears in mining records from at least the 16th century, when miners needed language to describe the slant they observed in underground seams and fractures.
Hade matters because it changes where your drill actually goes and what you extract. A vein that hades significantly may require angled drilling to intersect it efficiently. In hard rock mining, a hole that hades unintentionally (due to geology, tool wear, or operator technique) will miss its target zone. Core samples return angled rather than vertical, which complicates geological logging. Deep blast holes with excessive hade reduce fragmentation and waste energy.
Measuring and managing hade
Mining engineers track hade using downhole surveys, which use inclinometers or gyroscopes to measure deviation from vertical at intervals down the hole. Modern automated drilling rigs actively correct hade using steering tools and real time feedback. In open pit operations, blast holes are designed with controlled hade angles to optimize rock movement toward the pit. Underground, supporting a vein with significant hade requires different stope geometry and pillar placement than a near vertical one.
The word applies equally to natural features: a geologist mapping an ore body notes whether the mineralized zone hades east, for example. A fault that hades at 35 degrees presents different stability and groundwater behavior than a steep fault. In coal mining, seams that hade significantly were historically worked from the uphill side to avoid mining through thick roof or floor rock.
Hade is distinct from dip, though both describe inclination. Dip typically refers to the angle of a planar feature (like a bedding plane or fault) measured from horizontal; hade measures deviation of a borehole or shaft from vertical. The distinction matters when communicating between drilling and geological teams.