Collected on planet surfaces.
Technetium, Tc, atomic number 43. Melting point 2430K. Technetium in various isotope forms is used in medical imaging technology. It is also used as a catalyst. Its stable beta decay makes it suitable for calibration and radioactive testing.
Where to find specific materials
Check the materials rate on the system map
Use data from the Engineering Database and EDEngineer (an ingame overlay to track materials, data & blueprint progress).