Pronunciation: [klˈɔːɹɪtˌɔ͡ɪd] (IPA) 
Chloritoid (/klɔːrɪtɔɪd/) is a mineral that belongs to the chlorite group. The spelling of this word can be broken down into four distinct sounds: "k" + "l" + "ou" + "r" for "chlor" and "i" + "t" + "oi" + "d" for "itoid". The first part of the word comes from "chlorine" while the latter refers to the mineraloid nature of the crystal. Chloritoids typically have a greenish-brown color and are often found in metamorphic rocks.
Chloritoid is a mineral that belongs to the phyllosilicate group, specifically the epidote group. It is a greenish to brownish-gray mineral with a hardness ranging from 6 to 7 on the Mohs scale. Chloritoid has a monoclinic crystal system and typically forms prismatic or tabular crystals, although it can also occur in granular or fibrous aggregates.
The name chloritoid derives from its composition, as it contains a significant amount of chlorite. It usually forms as a result of regional metamorphism, particularly in low-grade metamorphic rocks such as slate and schist. Chloritoid commonly occurs alongside minerals such as garnet, muscovite, staurolite, and quartz.
When observed under the microscope, chloritoid appears as fine grains or aggregates with a greenish color. It displays a characteristic pleochroism, meaning it exhibits different colors when viewed from various angles. Chloritoid is known for its high birefringence, which causes light to split into two rays when passing through the mineral.
In terms of its chemical composition, chloritoid generally consists of aluminum, iron, magnesium, and silicon, along with trace amounts of other elements such as manganese and manganese. Its chemical formula is often expressed as (Fe2+,Mg,Mn)2Al4Si2O10(OH)4. Moreover, chloritoid is considered a metamorphic mineral indicator, as its presence helps to identify the pressure and temperature conditions under which metamorphism occurred.
The word "chloritoid" has its etymology rooted in the Greek language. It is derived from the combination of two Greek words: "chloros", meaning "green", and "eidos", meaning "form" or "shape". Hence, the term "chloritoid" can be interpreted as "greenish form" or "greenish shape". This name was assigned due to the characteristic green color often exhibited by minerals in the chloritoid group.
