Material progression skips usefulness, as demonstrated by cobalt vs silver. Both ores can be mined at the same tool level, but cobalt is more of a pre-silver material since "Environmental Resistance" is not a very valuable attribute, especially on higher difficulties. Cobalt should be mineable before silver, and be found in realms before silver; they both appear at the same time.
Other resources should likewise come in a reasonable progression, and/or be re-balanced so that their usefulness doesn't end the moment a new resource becomes harvestable.
