Final answer:
Gravity can be higher over a metal ore deposit due to its greater density compared to the surrounding earth materials. This results in a local gravity anomaly which is detectable with precision instruments. Such variations in gravitational pull also affect weight, as observed when comparing weights on different planets.
Step-by-step explanation:
The force of gravity can be either higher or lower over a metal ore deposit depending on the density of the ore. Gravity is a function of mass, and mass is directly related to density. Since metal ores are generally denser than the surrounding earth materials, a metal ore deposit will have a greater gravitational attraction than the earth's crust without ore. This local increase in gravitational force is sometimes measurable with high-precision gravity meters, and is known as a gravity anomaly. Furthermore, gravitational force is generally weaker than electromagnetic forces such as those observed with magnets, as mentioned in relation to our daily experiences where a magnet can lift a paperclip against the gravitational pull of the entire Earth.
However, when considering large masses such as ore deposits, the gravitational pull can become significant enough to be detected by sensitive equipment. It is this variability in density that affects our weight which is the force of gravity acting on a mass. Just like we would weigh less on planets with a weaker gravitational pull like Mars or the Moon we would also register a slight difference in weight above a dense metal ore deposit due to its stronger gravitational pull.