calcite - calcite cleavage rhombs from China - Unit of 12 smaller student specimens
Calcite, CaCO3, is an extremely common rock forming mineral. In pegmatites it forms large masses and it makes up some limestones almost entirely. It has a large variety of crystal forms, but these do not include the rhombus-shaped pieces that are sold as “calcite crystals.” The rhombs are produced by cleaving calcite in three directions between rows of atoms.
When calcite is free of impurities and is optically clear, it exhibits double refraction. When it is placed above a line drawn on paper and rotated, the drawn line doubles and becomes single depending on the angle of rotation. Some of these specimens are clear enough to demonstrate this. These smaller cleavage rhombs are a decent size for your students. The pencil is 5 1/2" long, for scale.
We challenge you to find better student specimens from any supplier. These are clean sharp rhombs of clear calcite from China. Clear specimens give double refraction. The photos are representative of what we ship.
Click photo once to select, then again to enlarge.
Making multiple purchases? Click on the "combine shipping" button in the shopping cart. We'll send an invoice with combined shipping. A link in that invoice will bring you back to checkout, no hassle.
Shipping: By Priority Mail or USPS Ground Advantage, whichever is cheaper. Click > here < for shipping rates. See comment at Note! Use back button to return to this page.