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- Andrew Alden
- Bornite. Bornite is bronze in color with a bright blue-purple tarnish and has a dark-gray or black streak. This mineral has a hardness of 3 and the chemical formula is Cu5FeS4.
- Chalcopyrite. Chalcopyrite is a brassy yellow with a multicolored tarnish and a dark-green or black streak. This mineral has a hardness of 3.5 to 4. The chemical formula is CuFeS2.
- Native Copper Nugget. Copper has a red-brown tarnish with a copper-red streak. Copper has a hardness of 2.5 to 3.
- Copper in Dendritic Habit. Copper is red with brown tarnish and a copper-red streak. It has a hardness of 2.5 to 3. Dendritic copper specimens are a popular rock-shop item.
- Galena
- Iron Pyrite
- Native Copper
- Pyrrhotite
- Bornite
- Chalcopyrite
- Hematite
- Magnetite
- Native Gold
Galena is a primary ore of lead. specifically, it’s lead sulfide. Long used for both it’s cosmetic properties and as a base for the dull metal, it’s got a long history alongside humanity. Surprisingly, it first seems to have been used to help deter the sun from people’s eyes in the Middle East, before the toxic properties of lead were properly acco...
Iron pyrite is commonly known as Fool’s Goldfor the brassy color and metallic luster it presents. Iron pyrite is actually a form of iron sulfide, one of the two main varieties found. It forms into cubic crystals, but it’s also found scattered in various rocks where it presents as small, metallic glimmers. It was the bane of new prospectors during t...
Copper is an incredibly important metal for our civilization. While it’s mostly found in electrical wires and piping in our current age, it was among the first metals to be worked by humanity. Copper is simple to work, and it was often found in large quantities in its native form. From there all you need is a campfire and something to hammer with t...
Pyrrhotite is a strange mineral, but it’s essentially another iron sulfide. The difficulty in describing it is in the fact that it’s non-stoichiometric, which means that the base mineral structure isn’t able to be defined with smaller numbers. It’s sometimes called magnetic pyrite, as the crystalline form is weakly magnetic in some cases. Pyrrhotit...
Bornite is sometimes called peacock ore, a name also used for the mineral chalcopyrite below. The mineral itself is a copper iron sulfide, with an orthorhombic crystal system. While fresh surfaces are generally coppery, bornite quickly oxidizes and takes on a variety of deep red, blue, green, and purple when exposed to air. It’s a common find in ar...
Chalcopyrite is another form of copper iron sulfide, this time with a brassy look. It’s sometimes sold as “Peacock Ore” since brief immersion in a weak acid like vinegar will cause the copper to tarnish with spectacular colors. It’s considered the most common of the various copper ores that humanity uses. Chalcopyrite can be distinguished in its cr...
Hematite is a black, metallic iron oxide. It’s one of the main ores of iron, remaining magnetic and it’s quite widespread. For collectors it’s often seen in many different forms, the glistening black makes it distinct and massive formations lend themselves to cutting shapes and odd beads out of the material without regard for saving the extra. It c...
Magnetite is another of the main ores of iron, and it’s often hard to distinguish from hematite since they share a similar crystal structure. It’s the most magnetic naturally occurring material due to its high iron content, and it’s used to this day in the production of iron and steel. In the distant past, it was often used as a primitive compass, ...
Of course, some of what glitters is gold. Native gold is one of the most important elements of human development. The lack of oxidation and ease with which it could be shaped made it an easy store of value, and to this day you can see artifacts made from gold that looks the same as the day they were finished. Gold has been responsible for huge migr...
The luster of a specimen is usually communicated in a single word. This word describes the general appearance of the specimen's surface in reflected light. Eleven adjectives are commonly used to describe mineral luster. They are: metallic, submetallic, nonmetallic, vitreous, dull, greasy, pearly, resinous, silky, waxy, and adamantine.
Lustre (mineralogy) Lustre ( British English) or luster ( American English; see spelling differences) is the way light interacts with the surface of a crystal, rock, or mineral. The word traces its origins back to the Latin lux, meaning "light", and generally implies radiance, gloss, or brilliance. A range of terms are used to describe lustre ...
In an introductory course, luster is a described as a property of light reflection that separates metallic from non-metallic minerals. Determining luster can be difficult for a beginner. A dark colored sample of weathered magnetite (metallic luster) might be mistaken for an earthy sample of hematite (non-metallic luster), but these two will ...
May 25, 2019 · Luster, also spelled lustre, is a simple word for a complex thing: the way light interacts with the surface of a mineral. This gallery shows the major types of luster, which range from metallic to dull. I might call luster the combination of reflectance (shininess) and transparency.
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Dec 16, 2022 · Minerals that have the shiny appearance of polished metal are said to have a metallic luster. Some could be used as mirrors. Well-crystallized pyrite is a good example. Other commonly metallic minerals include chalcopyrite (CuFeS 2), bornite (Cu 5 FeS 4), native copper (Cu), native gold (Au), hematite (Fe 2 O 3), and magnetite (Fe 3 O 4).
