1949 – The discovery of rare earth mineralization between Clark Mountain, a dominant peak in northeastern San Bernardino County, CA, and Interstate Highway 15 (formerly US 91 and Arrowhead Trail) occurred in April. The United States Geological Survey confirmed the bastnasite discovery and made a public announcement in November.

1950 – Molycorp became interested and bought these claims in February. Meanwhile, the Survey was mapping in detail the entire Mountain Pass Area. During the course of this work, an enormous rare earths deposit was found. Much of it was on the Sulphide Queen claims. Molycorp bought the Sulphide Queen property

1952 – Production of rare earths at Mt. Pass began in 1952 using the old gold plant and a new ball mill, and flotation cells from the Urad, CO molybdenum property. Mining started in an area averaging more than 15% rare earth oxide (REO).

1954 – By 1954, 120 - 60 ton carloads of concentrates had been shipped to the government stockpile completing the contract. Other markets for REO’s had not developed and the mine and mill only operated part-time.

1965 – Development of a new red phosphor for color television tubes created a great demand for europium and yttrium. Fortunately by 1965 the Colorado School of Mines Research Foundation and MCA had developed a process that could produce 99.9% europium oxide, 85% cerium oxide and 65% lanthanum concentrate. MCA built a $1.2MM europium oxide plant and by the end of 1965 Mt. Pass’ production had increased six-fold from the
previous year to 6.1MM pounds of REO concentrate.

1966 – A new concentrator was completed with a capacity of 600 tpd but was still too small for the demand and was increased to 1000 tpd. By the end of 1966 total production at Mt. Pass had quadrupled to 24MM pounds of REO concentrates.

1967 – The concentrator at Mt. Pass was once again expanded. It was now operating at 1,200 tpd; and production of cerium concentrate was produced at a new $225M plant.

1977 – Molycorp was acquired by Union Oil Company of California (UNOCAL) in August.

1981 – Due to the continued expansion of the rare earths market a new $15MM Separations Plant was completed to produce samarium (Sm) and gadolinium (Gd) oxides up to 99.999% purity by solvent extraction (SX). Essentially the world market for Sm was sold out as it was discovered that combining Sm with cobalt (Co) created a very strong permanent magnet. Gd was produced for phosphors that reduce patient exposures to x-rays. Subsequently the plant was modified to produce high-purity terbium oxide for fluorescent lighting.

1989 – In 1989 Molycorp began to produce dysprosium oxide and increased its output of neodymium products required by the growing neodymium-iron-boron permanent magnet industry.

1990 – Rare earths processing facilities at Molycorp’s Mountain Pass mine in California had been greatly expanded to produce the unique concentrates that accounted for 40 percent of world-wide rare earths revenues.

2000 – Due to record lows in the rare earths market, Molycorp temporarily curtailed its mining operations and began primarily packaging and selling stockpiled product.

2005 – UNOCAL was acquired by ChevronTexaco in August.

2008 – Rare Earth Acquisitions LLC, acquired the Mountain Pass facility and established Molycorp Minerals.