Science Report
19 Dec 2012
April Davis
Today was all lab work and wistfully staring out of the window. At least there will be less snow on Mars. I was able to clean and examine some of the rocks that I picked up during previous EVA’s. One of the first rocks we examined was light grey with many fractures. It was 4-5 on Moh’s hardness scale, had a semi-glassy luster, and did not appear to have any cleavage. This rock looks a lot like chert with many dark fractures. I doubted it would have an HCl reaction, but I could not identify it and needed to do my due diligence. Much to my surprise, and the surprise of my crewmates and the film crew, the drop of HCl lightly effervesced as soon as it touched the sample! An HCl reaction is when hydrochloric acid reacts with a carbonate such as CaCo3 and releases carbon dioxide (CO2). While it could not be confirmed, I believe the specimen is a piece of a prehistoric bryozoan colony, likely from the Cretaceous Period because it was found on the Dakota Sandstone. At this point, I have decided to take the sample to one of my professors rather than destroy it to determine its components.
Another interesting find on Hab Ridge (Dakota Sandstone) was a round formation the size of a grapefruit, measuring one on Moh’s hardness scale. In the suit it is quite difficult to evaluate the rocks and minerals that we come across: you cannot see as clearly; you cannot feel the sample; you cannot use a hand lens. After getting back to my lab, and getting out of my suit, I was very excited to see that it had a spongy, porous texture and was definitely my first bit of caliche. To be sure I scraped some of the sample into a dish and released a drop of HCl, which fiercely effervesced. Since we were snowed in, and I have a lab (that will be greatly missed), I decided to have a little fun. I ground a small portion of the calcareous mineral and mixed it with distilled water. I hypothesized that the pH of the solution would be above nine. I tested the pH a few times, but was disappointed that the litmus paper did not turn blue. I have been notified that the ground mineral and distilled water would have made a basic solution and would have tested as a base, but I did not let it sit long enough.
It is tempting to scrape a bit more of the sample and test for pH again, just as it is tempting to chip away at my possible bryozoan colony. However, I cannot bring myself to destroy something that has taken millions of years to form. This inclination towards preservation might slow progress in the interim, but I firmly believe that I have an obligation to temper my desire for knowledge with appreciation of the Earth’s geologic process. I may not be able to identify all of the amazing rocks and fossils that I find out here, but I would rather take the slow road than obliterate everything in my path. I hope that you all enjoy hearing about my findings, even though I am not always sure of what I have found.