Link: https://www.curseforge.com/min…ods/underground-materials
Description:
Join into an underground travel looking for new material to enhance your Minecraft experience.
You'll be able to find some precious ore such as Ruby, Cobalt, Topaz, Amethyst and blocks like Marble, Basalt and Limestone to make precious buildings.
There are more things, but you'll need to discover them
Armors and tools aim to be balanced for a better experience and some of them are vanilla counterparts.