I have compiled a list of sources for the elements that are available to the amateur chemist. Strontium will be discussed here.
Strontium is a relatively soft, gray alkaline earth metal. It is highly reactive and must be stored under oil to prevent reaction with air. Strontium can replace calcium in bones, making radioactive strontium particularly dangerous to the bones. However, stable strontium is harmless. Strontium is very similar to calcium, with a slightly soluble oxide and colorless divalent compounds. Strontium compounds have a bright red flame when heated, making them useful for pyrotechnics.
In element form: No sources found.
In compound form: Strontium oxide is used in old CRT screens to absorb the radiation (lead cannot be used in the front of the tube because it darkens). Ceramic magnets are made of sintered strontium ferrite, as well as most ferrite cores. A few toothpastes contain strontium chloride. Flares and red fireworks often contain strontium.
Here is my sample of strontium. It is a ferrite core used to absorb electromagnetic inconsistencies.