General discussion, page-126

A technical article into lepidolite, spodumene and other types of hard rock lithium ores. All in costs, it looks like lepidolite quickly becomes cheaper to process once the price of spodumene concentrate is over $1000/t (price dropped from the previous highs to a current low of around $3,700 USD in China - https://www.metal.com/Lithium/201906260003). The graph is overly crowded but shows that lepidolite is more competitive with higher spodumene/lepidolite concentrate prices and higher volumes due to the valuable by-products that increases the comprehensive income therefore reducing processing costs.

Source of information below: https://www.sciencedirect.com/science/article/pii/S2096519223008601 on January 2023. Title - "Lithium extraction from hard rock lithium ores (spodumene, lepidolite, zinnwaldite, petalite): Technology, resources, environment and cost"


Note: The sulfuric acid process is the mainstream process for extracting lithium from spodumene which does include a roasting step as well.

Looks like 4 of the 5 top lithium extraction companies in China use lepidolite ore with the only exception being CATL.
https://www.tycorun.com/blogs/news/top-5-mica-lithium-extraction-companies-in-china-in-2022