1. Common Noun: This is the most basic kind of noun. When referring to the digging tool, it is a common noun.
2. Proper Noun: It could be a proper noun if it refers to a specific person, place, or thing, such as "Spade" as a last name or a name of a company.
3. Collective Noun: It could also be a collective noun if it refers to a group of spades, like "a set of spades" or "a deck of spades".
4. Abstract Noun: In some cases, "spade" can be used metaphorically to describe something like "a spade in the hand is worth two in the bush." In this case, "spade" is representing the idea of immediate action or tangible value, making it an abstract noun.
To determine the specific type of noun, you need to consider the context in which it is used.