<Li> Wackes are texturally dirty sandstones that have a significant amount of matrix . </Li> <P> Cement is what binds the siliciclastic framework grains together . Cement is a secondary mineral that forms after deposition and during burial of the sandstone . These cementing materials may be either silicate minerals or non-silicate minerals, such as calcite . </P> <Ul> <Li> Silica cement can consist of either quartz or opal minerals . Quartz is the most common silicate mineral that acts as cement . In sandstone where there is silica cement present, the quartz grains are attached to cement, which creates a rim around the quartz grain called overgrowth . The overgrowth retains the same crystallographic continuity of quartz framework grain that is being cemented . Opal cement is found in sandstones that are rich in volcanogenic materials, and very rarely is in other sandstones . </Li> <Li> Calcite cement is the most common carbonate cement . Calcite cement is an assortment of smaller calcite crystals . The cement adheres itself to the framework grains, this adhesion is what causes the framework grains to be adhered together . </Li> <Li> Other minerals that act as cements include: hematite, limonite, feldspars, anhydrite, gypsum, barite, clay minerals, and zeolite minerals . </Li> </Ul> <Li> Silica cement can consist of either quartz or opal minerals . Quartz is the most common silicate mineral that acts as cement . In sandstone where there is silica cement present, the quartz grains are attached to cement, which creates a rim around the quartz grain called overgrowth . The overgrowth retains the same crystallographic continuity of quartz framework grain that is being cemented . Opal cement is found in sandstones that are rich in volcanogenic materials, and very rarely is in other sandstones . </Li>

Sandstone with abundant feldspar indicates this type of climate