Bukovskyite is an iron

Iron

Iron is a chemical element with the symbol Fe and atomic number 26. It is a metal in the first transition series. It is the most common element forming the planet Earth as a whole, forming much of Earth's outer and inner core. It is the fourth most common element in the Earth's crust...

 arsenate

Arsenate

The arsenate ion is AsO43−.An arsenate is any compound that contains this ion. Arsenates are salts or esters of arsenic acid.The arsenic atom in arsenate has a valency of 5 and is also known as pentavalent arsenic or As[V]....

 sulfate

Sulfate

In inorganic chemistry, a sulfate is a salt of sulfuric acid.-Chemical properties:...

 mineral

Mineral

A mineral is a naturally occurring solid chemical substance formed through biogeochemical processes, having characteristic chemical composition, highly ordered atomic structure, and specific physical properties. By comparison, a rock is an aggregate of minerals and/or mineraloids and does not...

 with formula: Fe₂(AsO₄)(SO₄)(OH)·7H₂O which forms nodules with a reniform (kidney-shaped) surface. Under a microscope, these nodules appear as a collection of minute needles similar to gypsum

Gypsum

Gypsum is a very soft sulfate mineral composed of calcium sulfate dihydrate, with the chemical formula CaSO4·2H2O. It is found in alabaster, a decorative stone used in Ancient Egypt. It is the second softest mineral on the Mohs Hardness Scale...

. Some can be seen with the naked eye and occur inside the nodules.

Bukovskyite was first described from pit heaps from the Middle Ages

Middle Ages

The Middle Ages is a periodization of European history from the 5th century to the 15th century. The Middle Ages follows the fall of the Western Roman Empire in 476 and precedes the Early Modern Era. It is the middle period of a three-period division of Western history: Classic, Medieval and Modern...

, where sulfate ores had been mined at Kank, north of Kutná Hora

Kutná Hora

Kutná Hora is a city in Bohemia, now the Czech Republic in the Central Bohemian Region.-History:The town began in 1142 with the settlement of the first Cistercian Monastery in Bohemia, Kloster Sedlitz, brought from the Imperial immediate Cistercian Waldsassen Abbey...

 in Bohemia

Bohemia

Bohemia is a historical region in central Europe, occupying the western two-thirds of the traditional Czech Lands. It is located in the contemporary Czech Republic with its capital in Prague...

, Czech Republic

Czech Republic

The Czech Republic is a landlocked country in Central Europe. The country is bordered by Poland to the northeast, Slovakia to the east, Austria to the south, and Germany to the west and northwest....

, and other old deposits in the vicinity. Only recently defined and acknowledged, it was approved by the IMA

International Mineralogical Association

The International Mineralogical Association is an international group of 38 national societies. The goal is to promote the science of mineralogy and to standardize the nomenclature of the 4000 plus known mineral species...

 in 1969.

Bukovskyite was collected a long time ago from the overgrown pit heaps by the inhabitants of Kutná Hora. It was used for poisoning fieldmice and other field vermin. This poisonous clay, known also by the place name as "clay of Kutná Hora"', was widely known and it was considered to be 'arsenic' (arsenic trioxide). In 1901 Antonin Bukovsky, a Bohemian

Bohemian

A Bohemian is a resident of the former Kingdom of Bohemia, either in a narrow sense as the region of Bohemia proper or in a wider meaning as the whole country, now known as the Czech Republic. The word "Bohemian" was used to denote the Czech people as well as the Czech language before the word...

chemist, who studied minerals of old pit heaps, proved it was an arsenate.