Alan Treiman (Lunar and Planetary Institute, Houston) has noted that this interpretation rests on the accuracy of the interpretation that the fine-grained carbonate areas are partly dissolved. It is possible that some other mineral soluble in alkaline water was intergrown with the carbonate, and this is what was removed. Lauren Browning (University of Hawai'i) and William Bourcier (Lawrence Livermore National Laboratory) question the McKay group's basic interpretation of the conditions under which carbonates, magnetite, and sulfides can form. Browning and Bourcier note that magnetite and sulfide can form under a wide variety of conditions, not only in alkaline solutions, and that there are many factors that affect the chemistry, such as the concentrations of dissolved calcium and sulfur. In fact, the increase in acidity caused by carbonate dissolution would cause the formation of magnetite and iron sulfide. Thus, a simple inorganic explanation is available to explain the minerals in the carbonate globules.