In the cone and quarter method, what is the relationship between the pile diameter and its thickness?

• A. Diameter 4x to 8x thickness
• B. Diameter equal to thickness
• C. Diameter 2x thickness
• D. Diameter 10x thickness

Answer: (A)

In the cone and quarter method, the shape of the stockpile is key for getting a representative sample. The pile is formed as a cone with a certain height (thickness) and a base diameter. Having the diameter about four to eight times the height keeps the pile wide and shallow enough to minimize segregation and surface bias, while still being stable and easy to handle. This ratio helps ensure material drawn from all parts of the pile represents the whole, which is essential when the sample is later quartered. If the pile were too tall relative to its diameter, the sample could be biased toward material from the top or bottom and the cone could be unstable; if it were too flat, the structure could be prone to disturbance and edge effects. Therefore, a diameter roughly four to eight times the thickness is the practical, effective range for this method.