THERE  ARE ONLY A VERY FEW TYPES OF GENUINE IVORY  THEY INCLUDE  but are not limited  to  the most popular and noteworthy items in any collection.The balance of carved  organic items include most bone , Magnesium Silicate and shell.I donot include plant life.ELEPHANT or mammoth tusk ivory comes from the two modified upper incisors.

 HIPPO, WALRUS and some BOAR  are  the most used and recognized .Always ask for verifying  identifiers in each of the above items .

Elephant has a series of(Schreger lines) crosshatch marks and long smooth growth lines and do yellow and split with age.

A cross-section of Hippo dentine with the aid of a 10X hand lens reveals a tightly packed series of fine concentric lines. These lines can be regularly or irregularly spaced. The orientation of the lines will follow the overall shape of the particular tooth.As are similar indicators in Walrus and Boar. 

Bone is a mineralized connective tissue consisting of dahllite, proteins and lipids. Compact bone, which is most often used as an ivory substitute, is extensively permeated by a series of canals through which fluid flows. This is the Haversian System.THIS also has small colored partials or porosity in  bone.

MAGNESIUM SILICATE is refered to As Merrisham and comes from Turkey, S.Africa ,and PENNSlyvania ,USA

PLEASE review all Items  that you intend  to purchase and Ask Questions most sellers do not know differences.