Arsenic is a semi-metal native element, which is famous for its toxicity. But native arsenic also forms interesting mineral specimens, often associated with silver minerals. And it is also important industrial metal.
Andalusite is a common aluminosilicate, which is very important for metamorphic petrology and ceramic industry. Despite its lack of perfect gemmy crystals, it can form outstanding specimens and rarely also faceted gemstones.
Pseudomalachite is a common dark green secondary copper mineral, forming nice botryoidal or drusy specimens. Its popular among mineral collectors and usually occurs together with many other copper minerals.
Anglesite is a secondary lead mineral, very popular because of its nice gemmy crystals with great luster. It forms by oxidation of galena and other lead ores, often accompanied by other interesting secondary minerals.