Beskar, also known as Mandalorian iron or Mandalorian steel, was an alloy that was used in Mandalorian armor and was notable for its high tolerance to extreme forms of damage. In its purest forms, the metal was durable enough to withstand a direct blaster shot and could repel lightsaber strikes. A superweapon created by the Mandalorian Sabine Wren and used by the Galactic Empire, called the Arc Pulse Generator, was capable of superheating the metal to the point that it would burn everything it was protecting to a crisp, such as Mandalorian warriors encased within their Beskar armor. However, Wren destroyed her weapon during the Mandalorian Civil War.
-Wookieepedia
Ingame Informations
Beskar is one of the best armors in the game. It is extremely light and very durable. large blocks have 15.000 HP and weigh 1000kg while small blocks have 600 HP and weigh 40kg. Beskar armor also has a 150% bonus against energy weapons.
Beskar Ore is only available on Concordia, the home world of the Mandalorians. While you can get Beskar Plates from all the trading outposts, it is very expensive. The best way is to get Beskar is to fly to Concordia and mine it there.
To make Refined Beskar, you need 6.67 Raw Beskar and 3.33 Refined Alum (2:1) in a Advanced Factory Assembler.