enow.com Web Search

Search results

1. Results from the WOW.Com Content Network

2. Chert - Wikipedia

   en.wikipedia.org/wiki/Chert

   Chert varies greatly in color, from white to black, but is most often found as gray, brown, grayish brown and light green to rusty red [9] [10] and occasionally as dark green. [11] Its color is an expression of trace elements present in the rock. Both red and green are most often related to traces of iron in its oxidized and reduced forms ...

3. Quartz - Wikipedia

   en.wikipedia.org/wiki/Quartz

   Quartz is, therefore, classified structurally as a framework silicate mineral and compositionally as an oxide mineral. Quartz is the second most abundant mineral in Earth's continental crust, behind feldspar. [10] Quartz exists in two forms, the normal α-quartz and the high-temperature β-quartz, both of which are chiral. The transformation ...

4. Quartzite - Wikipedia

   en.wikipedia.org/wiki/Quartzite

   Quartzite. Quartzite is a hard, non- foliated metamorphic rock which was originally pure quartz sandstone. [1][2] Sandstone is converted into quartzite through heating and pressure usually related to tectonic compression within orogenic belts. Pure quartzite is usually white to grey, though quartzites often occur in various shades of pink and ...

5. Porphyry (geology) - Wikipedia

   en.wikipedia.org/wiki/Porphyry_(geology)

   Porphyry (geology) Porphyry (/ ˈpɔːrfəri / POR-fə-ree) is any of various granites or igneous rocks with coarse-grained crystals such as feldspar or quartz dispersed in a fine-grained silicate -rich, generally aphanitic matrix or groundmass. In its non-geologic, traditional use, the term porphyry usually refers to the purple-red form of ...

6. Schist - Wikipedia

   en.wikipedia.org/wiki/Schist

   Schist (/ ˈʃɪst / SHIST) is a medium-grained metamorphic rock showing pronounced schistosity (named for the rock). This means that the rock is composed of mineral grains easily seen with a low-power hand lens, oriented in such a way that the rock is easily split into thin flakes or plates. This texture reflects a high content of platy ...

7. Flint - Wikipedia

   en.wikipedia.org/wiki/Flint

   Flint, occasionally flintstone, is a sedimentary cryptocrystalline form of the mineral quartz, [1][2] categorized as the variety of chert that occurs in chalk or marly limestone. Historically, flint was widely used to make stone tools and start fires. Flint occurs chiefly as nodules and masses in sedimentary rocks, such as chalks and limestones ...

8. World Cup 2014 - Costa Rica vs. Greece | The Huffington Post

   data.huffingtonpost.com/2014/world-cup/matches/...

   The 2014 World Cup in Brazil has begun. Check HuffPost's World Cup dashboard throughout the tournament for standings, schedules, and detailed summaries of each match.

9. Quartz-porphyry - Wikipedia

   en.wikipedia.org/wiki/Quartz-porphyry

   Quartz porphyry from the island of Alnö, Sweden. Phenocrysts of clear glassy rounded quartz and white orthoclase feldspar are set in a fine-grained matrix. Sample is just over 10 cm long. Quartz-porphyry, in layman's terms, is a type of volcanic (igneous) rock containing large porphyritic crystals of quartz. [1][2] These rocks are classified ...