The only use for malachite/copper at this moment is just for making radios, which are nice but underutilized due to the complexity, low population numbers and communication apps such as discord.
I was thinking if we could have people scrambling to collect malachite like it was iron or gold.
My friends, lets talk about 
INFRASTRUCTURE!!! 
In plumbing and wells you have a few different components that are needed and most of them will be using copper. The copper tubing ofc, well tanks to hold and push the water out through air pressure via air bladder (empty water pouch) and motors (copper wires wound up tightly).
If electrical where to be introduced, copper wires, mounting brackets to transport electricity over walls and structures, and transformers could be optional for lowering voltage to go before going to smaller items.
Also with the introduction water tiles possibility of hydro power along with oil and coal.
The way that this could be utilized is by being able to transport liquids from ponds, hot springs and even salt water but would suffer from corrosion over time.