Lithium has two primary sources, hardrock and brine. The USGS has historically reported a country's lithium output as concentrates of key lithium minerals of which spodumene, petalite, amblygonite and lepodite are the most common. Of these petalite is consumed by the glass market. Their lithium content varies somewhat, so each of the types has been converted to contained lithium using their unqiue lithium percentage. For some countries the USGS has only reported "lithium minerals"; for these the spodumene rate has been used. Brine production started during the 1980's as Chile came on stream. Brine production is reported as lithium carbonate, lihtium chloride and lithium hydroxide which have also been converted to contained lithium. The shorter preliminary reports published each year in January for the prior year report lithium production as lithium. The annual average price reported by the USGS seems to be for lithium metal but today lithium is priced as lithium carbonate equivalent (LCE) which has 5.323 times the weight of lithium; the price is for the full weight. not the contained lithium. Historical prices have been converted to LCE using the 5.323 multiplier to create some degree of price data continuity. Historically lithium prices have not had a public market.