Since arriving at the feature with notable resemblance to bacon, at least from orbit, Perseverance has found a range of ancient materials formed by the action of water, including some that were not expected on this episode of Mars Guy. Based on landforms that are remarkably similar to Delta deposits on Earth, and bind with spectral evidence for clay minerals, there's no doubt that water flowed into Jezero or Yezero crater billions of years ago, and created a lake. It's in the deep calm waters of a lake where mud can collect and later turn into mudstones. The so-called bacon strip was recognized many months ago as a good candidate for mudstones. This matters because mudstones are ideal places to capture and preserve evidence of ancient microbial life, if it ever existed on Mars. So this is a great place for Perseverance to collect samples for return to Earth. Here's Mars Guy for scale. Perseverance did indeed find the kind of fine-grained rocks expected of mudstones, but sampling them could be dicey. In two locations, the rock abrating operation intended to expose fresh surfaces for science measurements has crushed these rocks. This creates some risk for sample coring operation, which needs a stable surface, and risk that if the rock is soft, it could turn to powder and fall out of the sample tube inside the coring bit. That's what happened nearly one year ago in the first attempt to collect a core sample from a very different but weak rock. An unexpected feature of the bacon strip is what appears to be light-tone mineral veins. Similar veins were first found by the opportunity rover and recognized as fractures in bedrock filled by the mineral gypsum, a calcium sulfate with water stuck in its structure. The curiosity rover also encountered gypsum veins. Gypsum is so common on Earth that you're probably surrounded by it right now. It's in Dragool, also known as Gypsum Board, that covers the walls in most buildings. One of the veins discovered by Perseverance was zapped with the laser of the supercam instrument, which provides information on the elemental chemistry. The results have not yet been released, but it's a pretty safe bet that they show the composition of gypsum based on the similarities with known gypsum veins on Mars and Earth. Here's an example from a place I visited in Chile called Via de Marte, Valley of Mars, seems appropriate, huh? Gypsum veins form from sulfur-rich water that circulates through the rock fractures and precipitates this mineral. Perseverance has now started to investigate the thinly-laired rocks just up from the ones in the bacon strip. These likely are some of the first rocks produced from the sediments that built the delta and were deposited on top of the mudstones as the delta built out into Lake Jezero. Fortunately, the first grind into these rocks shows that they are stronger than the underlying mudstones, but close-up views with the Watson camera show that they contain some very coarse grains. So these are not the fine-grained sedimentary rocks that are best for preserving dead microbes if they were ever present. But Perseverance has barely begun to explore the delta deposits and is sure to encounter a smorgasbord of tasty rocks.