The investigation and interpretation of the composition of mineral deposits and related materials has in the past relied heavily upon the utilization of thermodynamic considerations based on equilibrium states. It has, however, become increasingly clear in recent years that chemical kinetic factors may play the dominant role in determining the nature, texture, and bulk properties of these materials. The present investigation was undertaken to clarify the situation with respect to the formation conditions and thermal and chemical stabilities of one class of substances of considerable current interest in geochemistry, mineralogy, archeology, and corrosion science; viz., the copper (II) hydroxy- and oxychlorides. Part I of this work deals with the mechanism of precipitation of the polymorphs of copper (II) trihydeoxychloride from aqueous solution, and elucidates the factors that determine the crystal character of the final precipitate. Part II explores the thermal stabilities and mechanism of phase transformation of copper (II) chloride dihydrate; copper (II) hydroxychloride, CuOHCl; the polymorphs of copper (II) trihydroxychloride, Cu*l2*s(OH)*l3*sCl; copper (II) oxychloride; and copper (II) oxide.