Travertine

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Travertine
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Travertine

• Sedimentary Rock
• Carbonate precipitate usually aragonite which
  alters to calcite
• Often deposited from hot mineral springs
• Porous version called Tufa

http//en.wikipedia.org/wiki/Travertine
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Physical Characteristics- Aragonite

• Chemical Formula CaCO3
• Composition Calcium carbonate, sometimes with
  some strontium, lead, and zinc.
• Variable Formula(Ca,Sr,Pb,Zn)CO3
• Color Colorless, white, brown, gray, yellow,
  reddish, pink, purple, light blue, light green
• Streak White
• Hardness 3½ - 4
• Crystal Forms and Aggregates (Orthorhombic) Very
  rarely occurs in single, untwinned crystals. The
  most common crystallized form is in
  pseudohexagonal trillings, which can be in the
  form of long, slender, prismatic crystals or
  short stubby ones. Many other forms exist in
  Aragonite, such as acicular, radiating, fibrous,
  columnar, stalactitic, botryoidal, pisolitic,
  oolitic, tuberose, granular, and ball-like
  protrusions of pseudohexagonal crystals.
• Transparency Transparent to opaque
• Specific Gravity 2.9 - 3.0
• Luster Vitreous, resinous, dull
• Cleavage 3,1 - prismatic indiscernible,2
• Fracture Subconchoidal
• Tenacity Brittle
• Other ID Marks 1) May fluoresce blue pink, or
  yellow 2) Clear specimens exhibit a strong double
  refraction

http//www.minerals.net/mineral/carbonat/aragonit/
aragonit.htm
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Occurrence

• Hot springs
• Sedimentary deposits
• Yellowstone National Park

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Uses

• Dimension stone ornamental stone used in
  construction
• Tile
• Medium for carving

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http//en.wikipedia.org/wiki/ImageTravertineUSGOV
.jpg
http//en.wikipedia.org/wiki/ImageYellowstone_p11
00309_rotated.jpg