Ferruginous Quartz. Not a very pretty name. It does not illicit gasps of joy. No one is running out to buy it. Well…………wait a minute!
You probably have a hematoid quartz in your collection. How about a Harlequin Quartz? Fire Quartz? Red Quartz? Then what you technically have……..is Ferruginous Quartz.
So let’s start at the beginning.
Ferruginous is defined as : of, relating to, or containing iron 2: resembling iron rust in color.
Quartz is defined as: a mineral consisting of silicon dioxide occurring in colorless and transparent or colored hexagonal crystals or in crystalline masses
“Ferruginous Quartz is a macrocrystalline type of quartz that is more or less evenly colored in yellow, red, or brown tones by inclusions of iron compounds, usually iron oxides (hematite) and hydrous iron oxides (limonite or inclusions of goethite can cause a deep yellow color,).” http://www.quartzpage.de/eisenkiesel.html
There are several combinations that can make up a Ferruginous Quartz. Inclusions may include ONLY hematite (red to dark red brown), ONLY Limonite or a Goethite/Limonite combination (mustard to yellow) OR combinations of hematite/limonite or hematite/limonite/goethite. There also may be a load of trace minerals, but that is another story for another day.
The red combinations (blood red, brown red, orange red) are most likely Hematite inclusions. These are a variety of Ferruginous Quartz. Hematite has a wide range of colors, depending on the intensity of the iron oxides present. These include rust red, blood red, orange/red, reddish brown and black.
Ferruginous Quartz with Limonite/Goethite
The more golden colored crystals, polished shapes or tumbles are more likely colored by Limonite/Goethite inclusions. These are a variety of Ferruginous Quartz. Limonite has a wide range of colors, depending on the intensity of hydrous iron oxides present, which can include yellow-brown, light brown to brown.
In my research, I found a large number of crystal selling sites that ID’d all of their ferruginous quartz as Hematoid quartz. Or would use the names interchangeably on pieces that obviously were not the same. This mislabeling does such a great disservice to buyers.
In fact, I found so many specimens that were the same but with different marketing names, that I thought I would start my own “cheat sheet”.
Ferruginous Quartz with Hematite
“Fire Quartz” is a marketing name for any bright red, hematite included Quartz. Also called Red Quartz, or Hematoid Quartz. It is a variety of Ferruginous Quartz.
Also included under the umbrella of Ferruginous or Hematoid quartz would be any phantoms of Hematite included in quartz. They can range in color from the bright orange phantoms from Namibia to the blood-red phantoms from Orange River, Africa to the red tipped Amethyst from Thunder Bay, Canada. These are all phantomed quartz’s and would most accurately be defined as Quartz with hematite inclusions, Hematoid Quartz (or in the Thunder Bay specimens, Quartz Var. Amethyst with hematite inclusions) or simply Ferruginous Quartz.
“Harlequin Quartz” (trade name or marketing name) is defined as a quartz crystal with inclusions of Hematite and Lepidocrosite. Usually, this will normally have more dots or “strings” included in the Quartz. While there are inclusions of Hematite, I would not consider this Fire Quartz (although many sellers lump these two names together) as there is the additional inclusion of Lepidocrosite.
Would it still be considered Hematoid Quartz? Ferruginous Quartz? Technically, yes.
Specularite or Specular Hematite is not the same at all, although it is used interchangeably or suggested it is a synonym of Hematoid Quartz on many sites. Specular Hematite is the sparkly black variety you may see in free forms. They grow on the OUTSIDE of quartz. They are not an inclusion IN quartz.
Specularite or Specular Hematite is usually coated with a thick layer of clear resin because of the fragility of the pieces. There are also many specimens that are naturally occurring.
Check out my other Breaking Down articles, like this one on Amber!