Cataract brunescens results due to deposition of-
Urochrome
Copper
Iron
Silver
In nuclear senile cataract, there may or may not be assosiated deposition of pigment urochrome and/or melanin derived from amino acids in the lens. commonly observed pigmented nuclear cataracts are amber,brown(cataracta brunescens)or black(cataracta nigra) and rarely reddish(cataracta rubra) in colour. REF IMG
Lens