The following is my understanding. Please correct me where I am wrong.
1) Stick-on weights are either lead or iron. There are not any zinc stick-on weights.
2) Clip-on weights are either lead, zinc or iron. Each category is in a relatively pure form.
A scrape metal dealer has some "strips" that he claims contain lead. They are about 1.5" wide, about 1/8" thick and various lengths. They appear to be some type of composite; not pure lead. They have a heavier than expected feel for the size of each piece. They had a glandular inside appearance when cut. They are easy to bend and tend to comeback, somewhat, to its original shape. A lighter will not ignite the material with a long attempt at lighting. Does anyone have an idea what this material is and if it does actually contain lead?