Other studies suggest the colors are associated with the increasing content of lead, rubidium, and thallium ranging in amounts between 0.00X and 0.0X in the feldspars, with even extremely high contents of PbO, lead monoxide, (1% or more) known from the literature.
Research indicates that the colors of these minerals are linked to varying levels of lead, rubidium, and thallium, with concentrations ranging from 0.00X to 0.0X in feldspars.  The literature also documents extremely high amounts of PbO (lead monoxide), exceeding 1% in some cases.