Thulium is often found with minerals containing yttrium and gadolinium. They include gadolinium and manganese chelates, or iron salts for T signal enhancement. The most commonly used intravenous contrast agents are based on chelates of gadolinium. Gadolinium-153 is produced in a nuclear reactor from elemental europium or enriched gadolinium targets. This isotope is produced in a nuclear reactor from europium or enriched gadolinium. They replaced the commonly used YSZ electrolyte with a CGO (cerium gadolinium oxide) electrolyte. Gallium is also used in the production of artificial gadolinium gallium garnet for jewelry. Cardiac magnetic resonance shows the characterization of myocardial tissue through patterns of gadolinium enhancements. MRI with gadolinium enhancement is the most useful neuroimaging test. The next major application is for gadolinium gallium garnets. Only gadolinium and samarium occur in nature; the rest are synthetic. Toxicities have not been reported following low dose exposure to gadolinium ions. Gadolinium as a phosphor is also used in other imaging. However, gold, platinum, mercury, and some lanthanides such as gadolinium have applications as drugs. The magnetic moments of gadolinium compounds are larger than those of any transition metal ion.