North-Central Section - 49th Annual Meeting (19-20 May 2015)

Paper No. 2
Presentation Time: 1:30 PM-5:30 PM


BELL, Grant C., Augustana College, 639 38th St., Rock Island, IL 61201,

Textural analysis of crystals and rocks is a useful means of identifying their origins. A closer look at nucleation in fast growing crystals as a proxy for real world geologic processes should be able to better explain the textures of various crystal beds and evaporite deposits. Attempts at understanding a relationship between temperature, substrate, and nucleation with final crystal growth have been made by examining data collected from lab experiments. Crystallization variables including solution composition and concentration, as well as temperature and duration of precipitation are being investigated. More than 20 experiments have been performed using a solution of sodium chloride and deionized water in plastic petri dishes. In these experiments the concentration of sodium chloride has been varied as has the total volume of solution used. Heat was evenly applied to the tests via a contained water-bath apparatus set on a ceramic hot plate in order to accelerate crystal nucleation and growth. Various concentrations of sodium chloride in solutions have yielded results that may demonstrate a relationship between original nucleation sites and the texture of the salt crystals. At this time, lab experiments suggest that at greater temperatures, ranging from 45-95° C, nucleation sites are more evenly distributed across the base of the petri dishes. A greater concentration of sodium chloride also seems to yield an even distribution of nucleation sites although there are fewer sites present, instead hosting larger crystals. Future experimentation involving other salts and compounds including magnesium chloride, potassium chloride, and calcium sulfate, as well as continued experiments with sodium chloride will be performed in order to clarify and confirm these results and to more accurately mimic natural evaporite deposits.