What is the difference between galena and hematite

For example, pure quartz SiO 2 , is colorless, whereas amethyst a variety of quartz , which has traces of iron in it, has a strong purple color.

Rose quartz's pink color is caused by traces of titanium or manganese. Certain minerals will exhibit a color change when exposed to light, heat, or radiation. Realgar will transform into orpiment , and orpiment will crumble into a light - yellow powder if exposed to light. Some minerals, such as proustite, vivianite, fluorite , will darken upon prolonged exposure to light, whereas other minerals, such as kunzite spodumene will fade. Most secondary copper minerals show a bright blue and sometimes green color.

Iron will usually cause a mineral to exhibit a dark red or brown, and manganese is responsible for the coloring of many pink minerals.

Some minerals, such as cassiterite and zincite , have chemical structures that would cause it to be colorless, but due to impurities and other factors, they are never found colorless. Most secondary uranium minerals exhibit either a bright neon yellow or green color. Minerals containing, aluminum, sodium, and potassium, are usually colorless or very lightly colored. In some cases, a mineral's color can depend on its atomic bonding rather than composition, such is the case in the difference between diamond and graphite.

They both have the same elemental makeup - Carbon C , yet one is almost always white to very lightly colored, while the other is always grayish black. Some minerals can tarnish, thereby affecting the color of the specimen. The best examples are silver tarnishing black, copper tarnishing green, and bornite tarnishing to a play of different colors.

Some minerals, such as opal a variety of quartz , display a multicolored effect when viewed from different angles. This is called opalescence. A few minerals appear to change color when viewed in different light.

Alexandrite is dark green in natural light, but takes on a purplish hue when seen in artificial light. Other minerals will change to a different color when viewed from different angles. This is called dichroism. Cordierite has the greatest dichroic ability of any mineral, such that a blue purplish crystal will turn gray when rotated.

Streak is the color of a minerals powder when it is crushed. Some minerals have a different color powder than their actual color. Every mineral has an inherent streak no matter what color it is.

For example, calcite occurs in many different colors, shapes, and varieties. But every single variety of calcite has a white streak. Streak is useful to distinguish two minerals that have the same color, but a different streak. A fine example is distinguishing gold , which has a yellow streak, and pyrite , which has a black streak.

Another example is distinguishing magnetite , which has a black streak, and hematite , which has a reddish streak. Most light colored, nonmetallic minerals have a white or colorless streak, as do most silicates, carbonates, and most transparent minerals.

We classify minerals according to the anion part of the mineral formula, and mineral formulas are always written with the anion part on the right.

Minerals with only one element such as S are native minerals, while those with an anion from the halogen column of the periodic table Cl, F, Br, etc. Provide group names for the following minerals:. Skip to content Chapter 2 Minerals.

Exercise 2. Previous: 2. Next: 2. Have them write down the vocabulary words as you put them on the board, and discuss what they mean using the mineral specimens. Use the following specimens from the kit to explain each word in the vocabulary list. If you have better specimens, use them instead. They are light. This is an optical property. Ulexite brings the picture up toward you, like a television. Calcite makes two images. Comparing characteristics of minerals.

It is also used for making jewelry items. With atomic number 79, gold is a chemical element. It is soft, shiny and dense metal. It appears bright yellow is pure form. It is resistant to acids but dissolves in aqua regia. Gold is considered as a precious metal and used for making jewelry since long. Hematite is an iron oxide, which is found in black, gray and radish brown colors.

Iron is chemical element, which is soft in pure form. Many other elements are mixed with iron to make alloys. Galena is lead mineral, mixed with sulfide. Galena is used for making batteries and wireless sets. On the other hand, chalcopyrite is copper iron sulfide mineral, used for making copper pipes and coins.