This is why spinel and ruby are often found together.

It is believed to be the second largest spinel in the world.

Some natural spinel is also a deep black and could serve this same purpose.

As of 2013 manganese spinel was used in commercial cells.

This layer is a spinel structure only a few atoms thick.

"Unfortunately, it is only a spinel, identified as such in recent years.

A spinel is a gem stone found in various color varieties, among them red.

It is an oxide mineral belonging to the spinel group.

Spinel can be highly detrimental because of its big size and high hardness.

Some of these are glass, and others have spinel and pyroxene.

Red spinel may be mistaken for ruby by those lacking experience with gems.

It belongs to the spinel group and forms tetragonal crystals.

It is in the spinel group and forms a solid solution series with magnetite.

The spinel begins as a material that looks like talcum powder and is broken down further.

It is actually a large red spinel.

The nickel atoms are organized corresponding to a "normal" spinel arrangement.

Additionally, its distribution in the precursor spinel powders is of critical importance.

The occurrence of this spinel does not easily fit with current lunar-crustal evolution models.

It was only relatively recently that the rarer ruby has been differentiated from the more common spinel.

So you are viewing not the world's largest ruby, but a fine specimen of spinel."

"Merely a form of spinel, though this is a fine specimen, which I doubt that anyone could match.

The ordinary refractive index, N, is high, comparable with spinel (1.719).

It commonly contains a few percent chromium-rich spinel as an accessory mineral.

For example in this way a ruby can be distinguished from a red spinel which is not pleocroitic.

The a-axis and the b-axis is the half diagonal of the spinel unit.