Per a Parker brochure introducing this nib material on the Parker 51 model, Octanium is an alloy composed of eight different metals, each chosen for certain attributes:
Strength and hardness:
40% Cobalt
15% Nickel
20% Chromium
High resilience:
7% Molybdenum
2% Manganese
15% Iron (approximately)
Additional strength against all stresses and climatic conditions:
0.04% Beryllium
0.15% Carbon