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  2. Coal - Wikipedia

    en.wikipedia.org/wiki/Coal

    Coal is a combustible black or brownish-black sedimentary rock, formed as rock strata called coal seams. Coal is mostly carbon with variable amounts of other elements , chiefly hydrogen , sulfur , oxygen , and nitrogen . [ 1 ]

  3. Bituminous coal - Wikipedia

    en.wikipedia.org/wiki/Bituminous_coal

    Bituminous coal is dark brown to black, [3] hard, [9] but friable. [10] It is commonly composed of thin bands of alternating bright and dull material. [9] Though bituminous coal varies in its chemical composition, a typical composition is about 84.4% carbon, 5.4% hydrogen, 6.7% oxygen, 1.7% nitrogen, and 1.8% sulfur, on a weight basis. [11]

  4. Anthracite - Wikipedia

    en.wikipedia.org/wiki/Anthracite

    An anthracite pile in Trevorton, Pennsylvania. Anthracite derives from the Greek anthrakítēs (ἀνθρακίτης), literally "coal-like". [9] Other terms which refer to anthracite are black coal, hard coal, stone coal, [10] [11] dark coal, coffee coal, blind coal (in Scotland), [7] Kilkenny coal (in Ireland), [10] crow coal or craw coal, and black diamond.

  5. Glossary of coal mining terminology - Wikipedia

    en.wikipedia.org/wiki/Glossary_of_coal_mining...

    Small coals may be produced accidentally by breakage, and sometimes deliberately as a by-product of screening out the more valuable round coals. Small coal at one time referred to charcoal, but this usage is obsolete. [31] Snap or bait. Snap, bait or piece is food taken to eat part way through the shift and often carried in a snap tin. [32] Sough

  6. Geology of Pennsylvania - Wikipedia

    en.wikipedia.org/wiki/Geology_of_Pennsylvania

    This section is a bit misleading since there are hills as high as 1,200 feet (366 m) in this section. It is separated from the rest of the Piedmont sections due to the distinctive rock types found here. Also called the Triassic Basin, most of the bedrock are red sandstone, siltstone, and shale. A few formations are brown and black.

  7. Pyrite - Wikipedia

    en.wikipedia.org/wiki/Pyrite

    Pyrite is the most common of sulfide minerals and is widespread in igneous, metamorphic, and sedimentary rocks. It is a common accessory mineral in igneous rocks, where it also occasionally occurs as larger masses arising from an immiscible sulfide phase in the original magma. It is found in metamorphic rocks as a product of contact metamorphism.

  8. Why is it called Black Friday? Here's the real history behind ...

    www.aol.com/news/why-called-black-friday-heres...

    According to the History Channel, the name was first used to describe an 1869 financial crisis, in which corruption and stock fraud caused the U.S. gold market to collapse entirely.

  9. Jet (gemstone) - Wikipedia

    en.wikipedia.org/wiki/Jet_(gemstone)

    Jet is a type of lignite, [1] the lowest rank of coal, and is a gemstone.Unlike many gemstones, jet is not a mineral, but is rather a mineraloid. [2] It is derived from wood that has changed under extreme pressure.