Characteristics of Lake Superior agates

What makes an agate an agate? In this section, we will explore the basic characteristics of the Lake Superior Agate.

First, there are the banding characteristics. The banding is the “stripes” that you usually see inside or on the surface a Lake Superior agate. Banding patterns are synonymous to the word “agate”. Sometimes, an agate may look like its bands have been peeled away. This is called “peeling”, and is effectively what happened over time. Bands come in many different shapes, sizes, sizes and colors; which brings me to the next characteristic; color.

Secondly, there is the color in the agate. Lake Superior agates encompass a wide range of colors and shades. Red, white, orange, yellow, and brown are colors prevalent in Lake Superior agates. There are also rarer colors, such as purple and green that occasionally show up.

Thirdly, there is the iron oxide staining. This is the yellow, red, or (less commonly) other shades. Most Lake Superior agates exhibit this feature, if not all of them. Usually, a big portion of the stone’s surface area is covered in iron oxide staining. There are two basic types of iron oxide staining in a Lake Superior agate. The first one is caused by a mineral known as hematite, and displays the red hues of iron oxide staining. For the most part, it is present on the banded areas of the agate. The second one is caused by a substance known as limonite, and displays the yellow hues of iron oxide staining. It is present on the outer layer of the agate, called the “husk”, and is also present on the banded areas that are exposed.

Then, there is the translucent characteristic of the agate. A translucent object is one that light can pass through, but not so much that you can see through it. The mineral that Lake Superior agates (and all agates) are made of is called chalcedony, and it allows translucence to occur. On days that the sun is shining, the Lake Superior agate may even “glow” to a certain degree.

Next, there’s the glossy or waxy appearance of the agate. When an agate chips, the resulting fracture is called a conchoidal fracture, named after the conch shell which it closely resembles. This fracture in agates is the same type of fracture in glass, and shows a glossy, waxy, appearance on Lake Superior agates.

Finally, there is the pitted texture or appearance of the agate. These are the pits, or “pockmarks” that you see on the husk of the agate. According to the multiple deposition theory, which involves silica sediment being deposited one layer at a time into the vesicle, usually until it fills completely (more on that later), this pitting occurs because there were deposits of minerals originally on the walls of the vesicle.

In conclusion, the primary characteristics of Lake Superior agates are banding, color, iron oxide staining, translucence, glossiness or waxiness, and pitting.