Short answers, pulled from the story.
The Genesis Rock, catalogued as sample 15415, is a piece of Moon rock retrieved by Apollo 15 astronauts James Irwin and David Scott in 1971 at Spur crater on the Moon. It weighs approximately 270 grams and is stored at the Lunar Sample Laboratory Facility in Houston, Texas.
Analysis of the Genesis Rock initially showed it to be 4.1 plus or minus 0.1 billion years old. Other research methods approximate its age at between 4 and 5 billion years old, placing it in the Pre-Nectarian period of the Moon's history.
The Genesis Rock is an anorthosite, composed mostly of a type of plagioclase feldspar known as anorthite. Anorthosites are thought to form when lighter minerals float to the top of a magma ocean and crystallize as the melt cools.
No. Research has shown that sample 14321, retrieved during the Apollo 14 mission, is older than the Genesis Rock. Sample 15415 is still an extremely old sample formed during the Pre-Nectarian period, but it does not hold the record.
Scientists originally believed the Genesis Rock was a piece of the Moon's primordial crust because its anorthosite composition matched what the earliest solid lunar surface was expected to look like. Later analysis showed it was only 4.1 billion years old, younger than the Moon itself, which ruled out the primordial crust interpretation.
Dating of pyroxenes from other lunar anorthosite samples using the samarium-neodymium method gave a crystallization age of 4.46 billion years. Broader research methods place lunar anorthosite formation between 4 and 5 billion years ago.