Rocks

Description of the Landscaping Rocks Next to the Walkway
By the UU World of Children

Six rocks have been placed along the walkway; starting at the left:

• The first rock (sedimentary) is a white to tan quartzitic sandstone, containing large hexagonal quartz crystals (SiO2) up to one-half inch in diameter. Close examination with a magnifying glass will show the predominant mineral in the rock to be quartz grains. The crystals formed when silica saturated groundwater seeped into voids in the original sandstone formation. When this occurred, conditions changed such that the groundwater could hold less dissolved silica. The excess silica was deposited on the sides of the voids, and over time, resulted in the hexagonal quartz crystals.

• The second rock (sedimentary) is also a tan to black, almost pure, fine grained, quartzitic sandstone. Examination under a magnifying lens or hand lens clearly shows the quartz consisting almost entirely of rounded, to sub rounded, quartz grains. The depositional environment of the formation from which the rock was obtained was most likely a beach.

• The third rock (metamorphic) is a weakly foliated (banded) biotite gneiss, containing biotite, quartz, and white to pink feldspars. A feldspar is a general term meaning field stone of granitic origin. The original rock which was metamorphosed was a granite.

• The fourth rock (sedimentary) is a reddish brown, fine grained, laminated sandstone, consisting predominantly of quartzite grains.

• The fifth rock (metamorphic) is a light brown to gray schist, with one half to one inch long black inclusions. The black mineral is not biotite, but probably in the amphibole or pyroxene family.

• The sixth rock (metamorphic) is a white to tan sillimanite schist. Sillimanite is a dense metamorphic mineral; Paris Mountain contains a fair amount of Sillimanite.

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