Travertine usually crystallizes as Aragonite . Onyx Marble, Suisan Marble, California Onyx, Oriental Alabaster, and Mexican Onyx - Travertine or Tufa with impurities causing it to exhibit color banding . Marble - Rock formed from calcium carbonate that re crystallized through metamorphism . Chalk - Rock composed of Limestone combined with the skeletal remains of tiny marine organisms. They are similar in many physical properties, and may partially or fully replace one another, forming a partial solid solution series .
Calcite is the one of the most common minerals on earth.
It occurs in a seemingly unlimited variety of shapes and colors. It constitutes a major portion of many of the earth's rocks. Calcite and Aragonite are polymorphous to each other. Although Calcite and Aragonite contain the same elements, they differ in crystal structure . Calcite forms trigonal crystals, whereas Aragonite forms orthorhombic crystals.