Main Page | See live article | Alphabetical index Spectrolite is a hard and rare variety of labradorite feldspar. Spectrolite is between 6 and 6.5 hardness and weighs 2.69 - 2.70 g/cc. Spectrolite was discovered by the Finns during WWII when building a defense line. After the war, spectrolite was mined in small quantities. This small supply made it more valuable. This article is from Wikipedia. All text is available under the terms of the GNU Free Documentation License.