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  2. Obsidian - Wikipedia

    en.wikipedia.org/wiki/Obsidian

    Obsidian was valued in Stone Age cultures because, like flint, it could be fractured to produce sharp blades or arrowheads in a process called knapping. Like all glass and some other naturally occurring rocks, obsidian breaks with a characteristic conchoidal fracture. It was also polished to create early mirrors.

  3. Apache tears - Wikipedia

    en.wikipedia.org/wiki/Apache_tears

    Apache tears are rounded pebbles of obsidian or "obsidianites" composed of black or dark-colored natural volcanic glass, usually of rhyolitic composition and bearing conchoidal fracture. Also known by the lithologic term marekanite , this variety of obsidian occurs as subrounded to subangular bodies up to about 2 in (51 mm) in diameter, often ...

  4. Mohs scale - Wikipedia

    en.wikipedia.org/wiki/Mohs_scale

    Hardness may be difficult to determine, or may be misleading or meaningless, if a material is a mixture of two or more substances; for example, some sources have assigned a Mohs hardness of 6 or 7 to granite but it is a rock made of several minerals, each with its own Mohs hardness (e.g. topaz-rich granite contains: topaz — Mohs 8, quartz ...

  5. Obsidian use in Mesoamerica - Wikipedia

    en.wikipedia.org/wiki/Obsidian_use_in_Mesoamerica

    Obsidian projectile point.. Obsidian is a naturally formed volcanic glass that was an important part of the material culture of Pre-Columbian Mesoamerica.Obsidian was a highly integrated part of daily and ritual life, and its widespread and varied use may be a significant contributor to Mesoamerica's lack of metallurgy.

  6. Knapping - Wikipedia

    en.wikipedia.org/wiki/Knapping

    Knapping is the shaping of flint, chert, obsidian, or other conchoidal fracturing stone through the process of lithic reduction to manufacture stone tools, strikers for flintlock firearms, or to produce flat-faced stones for building or facing walls, and flushwork decoration.

  7. Helenite - Wikipedia

    en.wikipedia.org/wiki/Helenite

    Helenite, also known as Mount St. Helens obsidian, emerald obsidianite, and ruby obsidianite, is a glass made from the fused volcanic rock dust from Mount St. Helens and marketed as a gemstone. [ 1 ] [ 2 ] Helenite was first created accidentally after the eruption of Mount St. Helens in 1980 .

  8. The best hiking shoes of 2025, according to hiking experts - AOL

    www.aol.com/lifestyle/best-hiking-shoes...

    When it comes to tackling the trails, footwear is one of your most important pieces of equipment. After all, the best hiking shoes are what stands between you and rocks, scree, and roots as you ...

  9. Sharpness (cutting) - Wikipedia

    en.wikipedia.org/wiki/Sharpness_(cutting)

    Sharpened metal drop-point blade Naturally occurring sharp obsidian piece Shark tooth with a sharp, serrated edge A sewing needle comes to a sharp point. Sharpness refers to the ability of a blade, point, or cutting implement to cut through materials with minimal force, and can more specifically be defined as the capacity of a surface to initiate the cut. [1]