 Metasandstone
This sample of metasandstone (or quartzite) displays stratified layers, revealing it’s probably sedimentary origin prior to deep burial and subsequent metamorphism. The difference between quartzite and metasandstone is that quartzite is of uncertain origin, it may have had a protolith of ether sandstone or volcanic ash. Both metasandstone or quartzite are extremely hard, and when broken will split through crystal grains rather than around them (like when breaking sandstone). This cobble is from river terrace gravel along the San Juan River, downstream of the San Juan Mountains of southwestern Colorado where metasandstone of Precambrian age occurs in abundance. |
| https://gotbooks.miracosta.edu/rocks/metamorphic/15.html |
2/2/2021 |
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