4.2" Red Cap Amethyst Crystal with Malachite - Thunder Bay, Ontario

In the 1950's amethyst deposits were discovered about 30 miles NE of Thunder Bay Ontario while building a road. Since the 1960's it has been mined in the area. The amethyst from Thunder Bay can range from light, delicate purples to almost black in color. One very distinctive characteristics of many Thunder Bay amethyst crystals is the the inclusion of red hematite (microscopic disks/spherules within the amethyst). These inclusions can cause crystals to have red highlights, zones or even appear completely red in color.

Amethyst is a purple variety of quartz (SiO2) and owes its violet color to natural irradiation, iron impurities, and the presence of trace elements, which result in complex crystal lattice substitutions. It’s considered a semi-precious gemstone, and just two centuries ago was considered to have a value on par with diamonds, sapphires and rubies. The largest and best known amethyst deposits occur in southern Brazil and Uruguay but many localities around the world produce an amazing variety of amethyst crystals and formations.

Silicon Dioxide, also known as SiO2 or Quartz, is the second most abundant mineral in the Earth's crust. Quartz crystals generally grow in silica-rich, hot watery solutions called hydrothermal environments, at temperatures between 100°C and 450°C, and usually under very high pressure. Quartz veins are formed when open fissures are filled with hot water during the closing stages of mountains forming, and can be hundreds of millions of years old.

Malachite is an intense green copper-based mineral that can be found in a wide variety of forms. Malachite can grow in botryoidal masses, stalactitic formations, and reniform formations, typically as a tight cluster of fanning fibrous needles that make up a seemingly solid mass. As layers continue to stack during formation, a banded pattern can sometimes begin to take shape, which explains the rings in all shades of green that are seen on most polished malachite specimens.

Malachite results from the weathering of other copper ores and is very often found associated with other copper-based minerals such as Azurite and Chrysocolla. It can be found in copper deposits around the world, but the Democratic Republic Of The Congo is the primary source for polished malachite and mineral specimens.

Malachite has been prized since ancient times, first as a utilitarian copper ore, then as an ornamental stone. Due to it's value as a decorative stone, it's rarely mined as a copper ore anymore.