Ten grams of previously analyzed, rock-forming silicate minerals (mica, 2.5 g) were ground under 100 ml of double-distilled, and CO 2 -charged, waters for one hour, and the centrifuged-clear solutions analyzed for dissolved constituents. The pH's of the slurries prepared in distilled water were 8 to 9, and in CO 2 -charged water, 5.5 to 6.9. Total amount of dissolved ions was higher in CO 2 -charged water than in distilled water. Grinding in distilled water was exposed to room temperature. Highest amounts in ppm of dissolved ions in distilled and CO 2 -charged waters, respectively, were from minerals as follows: Si, diopside, 23.3, and enstatite, 17.4; Al, nepheline, 2.2, and microcline 1.0; Fe, biotite, 14.3, none detectible in CO 2 -charged water; Ca, augite, 4.5, and hornblende, 13; Mg, enstatite and olivine, 12, and olivine, 150; K, microcline, 38.8 (K dissolved from 2.5 grams of biotite in distilled water was 35.4), and microcline, 69.3; Na, nepheline, 85.9, and nepheline, 114. Olivine dissolved nearly stoichiometrically (Mg and silica); aluminous and other Mg-rich silicate minerals show relatively reduced solubility of Si, some of which apparently combines with Al and/or Mg to form clay minerals. Dissolution of Mg is singularly much higher in CO 2 -charged water than in distilled water. No dissolved Fe was detected in CO 2 -charged water, demonstrating that residual concentration of iron oxide occurs by leaching of Fe silicates by carbonic acid. Elements extraneous to mineral formulas are enriched in the solution relative to others. Minor, or trace elements, such as Mn, Ga, V, Ti, Mo, Co, Sn, Pb, Zn, are dissolved in concentrations determined spectrographically in parts per billion.

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