I hand cut this freeform focal bead out of Kona Dolomite from the Kona Hills outside of Marquette in the Upper Peninsula of Michigan. Measurements in the title. CHAIN NOT INCLUDED.
A lot of what we call "marble" is mostly comprised of dolomite. Here's what June Culp Zeitner says in her book Gem and Lapidary Materials...."Marble is a crystalline calcareous rock formed by the metamorphism of limestone. The composition may be mainly clacite or dolomite, but impurities give this rock, which is white if pure, and artists palette of colors and a decorator's book of patterns....Marble has a hardness of 3....While limestone is sedimentary and marble is metamorphic, the term marble had been used to cover decorative materials in either group..." She goes on to comment specifically about Kona Dolomite, "This dolomite is a rock, not a mineral. The Lindberg quarry near Marquette has mined many tons of this elegant decorators' stone. Michigan cutters use this dolomite for fireplaces, doorways, counters, altars, and jewelry. The material also occurs as float over a large area. Kona dolomite has geometric and brecciated patterns and gracefully undulating bands with light muted ground colors dominated by a splendid coral pink, and accented with rust, brown, tan, and beige."
Some of the layers in this Kona Dolomite from Michigan are layers of fossil stromatolite, one of the earliest forms of life on Earth! It is believed that the stromatolites existence for a billion years or so changed the atmosphere enough to allow the conditions for more complex life. Here's some of what wikipedia has to say about Stromatolites, "are layered accretionary structures formed in shallow water by the trapping, binding and cementation of sedimentary grains by biofilms of microorganisms, especially cyanobacteria (commonly known as blue-green algae). They include some of the most ancient records of life on Earth....Stromatolites are a major constituent of the fossil record for about the first 3.5 billion years of life on earth, with their abundance peaking about 1,250 million years ago. They subsequently declined in abundance and diversity, which by the start of the Cambrian had fallen to 20% of their peak. The most widely-supported explanation is that stromatolite builders fell victims to grazing creatures (the Cambrian substrate revolution), implying that sufficiently complex organisms were common over 1 billion years ago."
Here's some info about Dolomite, courtesy of wikipedia..."Dolomite is the name of a sedimentary carbonate rock and a mineral, both composed of calcium magnesium carbonate CaMg(CO3)2 found in crystals. Dolomite rock (also dolostone) is composed predominantly of the mineral dolomite. Limestone that is partially replaced by dolomite is referred to as dolomitic limestone, or in old U.S. geologic literature as magnesian limestone. Dolomite was first described in 1791 as the rock by the French naturalist and geologist, Déodat Gratet de Dolomieu (1750–1801) for exposures in the Dolomite Alps of northern Italy."
According to Melody, in her Metaphysical book Love Is In the Earth, the properties of dolomite are, "encourages charitable actions and relieves sorrow in such a way as to assist one to recognize that there are actually no reasons to be sorrowful...encourages energetic and impulsive original thinking and manifestation. It also assists in producing stamina when dealing with hyperactive individuals."