What term is used to describe decomposed rock that can be dug with hand tools?

The term that describes decomposed rock that can be easily dug with hand tools is saprolite. Saprolite is a weathered rock that has undergone significant alteration through chemical weathering processes, resulting in a soft, clay-rich material that is relatively easy to excavate. This characteristic makes it distinct in geological contexts, particularly when assessing soil conditions for construction or agricultural purposes.

In contrast, granite is a solid and durable igneous rock that does not fit the criteria since it cannot be dug out with hand tools easily. Loam is a type of soil composed of a mixture of sand, silt, and clay, also not related to rock decomposition. Stratum refers to a layer of sedimentary rock or soil with internally consistent characteristics, and it does not specifically indicate decomposed material that can be dug by hand. Thus, saprolite is appropriately recognized for its unique properties that meet the conditions outlined in the question.