Apollo 15 astronauts David Scott and James Irwin collected an unusually bright white rock near Spur Crater on the Moon in August 1971, a sample later designated as the “Genesis Rock” that has become one of the most scientifically significant lunar specimens returned to Earth.
The fist-sized anorthosite, officially cataloged as sample 15415, has been dated to approximately 4 billion years old. Scientific analysis over subsequent decades confirms it represents a fragment of the Moon’s primordial crust, formed during the satellite’s early magma ocean phase when lighter plagioclase feldspar crystallized and floated to the surface.
Analysis: The Genesis Rock provided critical evidence supporting the lunar magma ocean hypothesis — the theory that the Moon’s outer layers were once entirely molten. Its near-pure anorthosite composition, rich in calcium-rich plagioclase feldspar, matches predictions for the earliest lunar crust formation. The sample continues to inform models of planetary differentiation and early solar system evolution.
The discovery occurred during Apollo 15’s second extravehicular activity at the Hadley-Apennine landing site. Scott and Irwin recognized the rock’s distinctive appearance immediately, with Scott describing it as “a piece of the original crust” during the live television broadcast. Mission Control in Houston confirmed the find’s significance in real time.
Subsequent laboratory analysis at NASA’s Lunar Receiving Laboratory and research institutions worldwide established the sample’s crystallization age through multiple radiometric dating methods, including samarium-neodymium and rubidium-strontium isochron techniques. The results consistently cluster around 4.0 to 4.1 billion years, placing the rock’s formation within the first few hundred million years of lunar history.
The Genesis Rock remains preserved at NASA’s Johnson Space Center in Houston, where it continues to be allocated for non-destructive and minimally invasive research as analytical techniques advance.
Sources:
– Times of India, “In 1971, Apollo 15 astronauts found an unusual white rock on the Moon — scientists later identified the Genesis Rock as part of ancient lunar crust about 4 billion years old,” https://timesofindia.indiatimes.com/science/in-1971-apollo-15-astronauts-found-an-unusual-white-rock-on-the-moon-scientists-later-identified-the-genesis-rock-as-part-of-ancient-lunar-crust-about-4-billion-years-old/articleshow/133561078.cms
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Story synopsis gathered from: Times of India – Top Stories — source
