The members of the IVA group belong to the fine Octahedrite class (Of.) They have a distinctive distribution of trace elements and include nodules of Troilite and Graphite with rare silicates. Apparently, this group originates in a small-differentiated asteroid that was fragmented in a collision, re-accreted, to be disrupted once again by a second collision.

Gibeon Meteorite:  Type: Iron Octahedrite; IVA
Specimens from Namibia, South West Africa.
Falling in prehistoric times, this meteorite was first reported in 1836 with many large masses found in a very large (estimated 70 by 230 miles) strewn field in intervening years. To account for the wide dispersal of fragments the meteorite is assumed to have broken up as it entered the atmosphere. A recent find was the Naco meteorite which has been paired with the Gibeon. This was a 25.2 kilogram fragment found in 1965 on Naco farm near the railroad station of Asab, South West Africa.
Most Gibeon specimens are large, unlike the Sikhote-Alin meteorite that also fragmented at very high altitude producing abundant small "shrapnel" specimens. We are therefore pleased to be able to offer these smaller, affordable, Gibeon specimens.
Structural Class: Fine octahedrite, Of, Widmanstätten bandwidth 0.3  - 0.05 mm.
Chemical class: Group IVA, 7.93% Nickel, 0.41% Cobalt, 0.04% Phosphorus, 2.0 ppm Gallium, 0.12 ppm Germanium, 2.3 ppm Iridium.

Muonionalusta Meteorite:  Type: Iron Octahedrite; IVA. 
The Muonionalusta meteorite fell in prehistoric times and was first reported in 1906. Additional finds were made in 1946 (15 kilograms) and 1963 (6.2 kilograms.) These meteorites were likely carried from the original place of fall by glacier action. Additional finds are likely. Octahedrites are composed of cubic Kamacite crystals with fine Taenite occupying the spaces between. The Taenite resists an acid etching solution that readily dissolves the large Kamacite crystals. The crystal pattern is readily seen after a light etch. That crystal pattern, revealed as "Widmanstätten lines" is clear in our particularly nice specimens showing the fine crystal structure of the IVA meteorite group. 
Structural Class: Fine octahedrite, Of, Widmanstätten bandwidth 0.3 - 0.05 mm.
Chemical class: Group IVA, 8.42% Ni, 2.24 ppm Ga, 0.133 ppm Ge, 1.6 ppm Ir.