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