How to get resources? | FAQ XCOM 2: War of the Chosen Game Guide

The resources in the game are divided into three groups - Supplies, Elerium and Alloys. They are used in various quantities to build facilities, develop new items for your soldiers, or produce items. Because of this, it is important to monitor their status on a regular basis and prevent any of the three groups of raw materials from being exhausted.

Having resources reserves.

The main sources are:

• Excavation - each excavation grants a considerable amount of resources. The deeper the room is located, the more resources it holds.
• Missions - sometimes you come across a place when you perform missions that, after being shacked, will give you a small (or large) injection of raw materials.
• Collecting on world map - you'll be informed about available resources with an appropriate prompt. After a few days of scanning, the resources will be extracted.
• Periodically granted by the Council - this is true only for Supplies. Every moth you will be granted access to new resources, but you still need to "scan" them on the world map.
• Completing missions sometimes also yields resources.
• Covert Action for the resistance. Some of these yield scientists or engineers.