calcite - variously colored cleavage rhombs - Unit of 5 large student specimens

Description

If making multiple purchases, please read the note following the
red text
below.
calcite -
CaCO
3
large
teaching
student specimens of variously-colored calcite from Morocco - Unit of 5 specimens
Calcite, CaCO
3,
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. These specimens are not clear enough to demonstrate this, but they are excellent examples of cleavage rhombs and are of a decent size for your students.
The pencil is 5" long, for scale.
We challenge you to find better student specimens from any supplier. These are clean sharp rhombs of variously-colored calcite from Morocco. The photos are representative of what we ship.
We will send some tiny rhombs with each set so you can demonstrate the calcium carbonate response to a drop of hydrochloric acid - it fizzes and releases carbon dioxide.
We really don't like the tiny finger nail-sized specimens offered to students, as we feel these are too small to see rock textures and too small for examining the identifying characteristics of a mineral. We collect these specimens so that five specimens, or possibly six, will fit in a small flat rate box, and we keep the price low, as we know these will be used in a classroom. For teachers we count like a baker and a dozen is more than 12, since you will always need a few spares.
If you are a teacher, let us know.
Making multiple purchases?
Just add items to your cart. When finished shopping, click on
“request total”
at upper right in the Shopping Cart window.
Do not proceed to checkout.
We will send an eBay invoice with the correct combined shipping.
The combined shipping will often be less than eBay shows. Please wait for that invoice before paying.
There is no obligation to purchase. You can decide after seeing what shipping will cost.
Shipping:
Ships in a small Priority Mail flat rate box unless combined with other purchases. We always combine shipping to get your purchase to you at the lowest cost. We do not charge for handling. We refund any overpayments on shipping beyond our actual cost. A second unit moves the shipment into a larger box. We can generally ship 4 to 5 student units or a number of hand specimens in that box with no further increase in postage.
We sell and ship internationally. If eBay’s page does not let you enter your country name to determine the shipping cost for something you are interested in, please contact us.  We can tell you what the shipping would cost and how to make the purchase. You can then decide if you wish to complete the transaction. Use the
Contact Seller
link in the Seller Information box on the right side of this page.
Pay securely with your debit or credit card through PayPal! You do not need a Pay Pal account to do this. Yes, we do combine shipping!