SEDA GEMS

QUARTZ WITH MARCASITE

This is a natural untreated stone from Brazil showing stunning marcasite floating inclusions in it.

This is a rare stone and considered a collectors item

Very well polished

Weight 23.64 cts app

Size 22x16x7 mm app

Marcasite Crystals common, metallic pale brass-yellow colored, tabular or pyramidal, often with curved faces; it may also be stalactic, globular, or reniform with a radiating internal structure. Frequently found replacing organic matter, forming fossils, in sedimentary beds, particularly coal beds.
May be intergrown or replaced by pyrite.

Quartz is the most common mineral on Earth. It is found in nearly every geological environment and is a component of almost every rock type.  It makes up about 12% of the earth's crust, occurring in a wide variety of igneous, metamorphic and sedimentary rocks. It is also the most varied in terms of variety and color.  Quartz is a 7 on the Mohs scale of hardness..

MICA-SCHIST, in petrology, a rock composed essentially of mica and quartz, and having a thin parallel-banded or foliated structure, with lamellae rich in mica alternating with others which are principally quartz. They split readily along the micaceous films, and have smooth or slightly uneven surfaces covered with lustrous plates of muscovite or biotite; the quartzose lamellae are often visible only when the specimens are looked at edgewise. Mica-schists are very common in regions of Archean rocks accompanying gneisses, crystalline limestones and other schists. Some have a flat banding yielding smooth slabs; others are crumpled or contorted with undulating foliation. Occasionally the quartz forms elliptical lenticles or "eyes." In some cases mica composes nearly the whole of the rock, in others quartz preponderates so that they approach quartz-schists and quartzites.