Any substance can be classified into a resource if it contains the following characteristics:
Usefulness: any resources must be useful for fulfilling any particular or multiple needs.
Limited: resources are also limited in nature. These cannot be limitless and therefore have to be conserved for future too
Needs processing and technology for usage: generally applicable to all resources, technology is required to make any substance to be used as a resource. In majority of the cases, such substances have to be processed before being used.
Inter-related: the use of one resource is generally related with another resource. A particular resource may be used more in the absence of a complimentary resource.