Striped flint (sometimes called banded flint) is a version of

flint Flint, occasionally flintstone, is a sedimentary cryptocrystalline form of the mineral quartz, categorized as the variety of chert that occurs in chalk or marly limestone. Historically, flint was widely used to make stone tools and start ...

, with a more or less regular system of concentric dark and pale stripes, noted to resemble rolling waters.

Use

A large striped flint deposit is located in

Lesser Poland Lesser Poland, often known by its Polish name ''Małopolska'' (; ), is a historical region situated in southern and south-eastern Poland. Its capital and largest city is Kraków. Throughout centuries, Lesser Poland developed a separate cult ...

, near the cities of

Sandomierz Sandomierz (pronounced: ; , ) is a historic town in south-eastern Poland with 23,863 inhabitants (), situated on the Vistula River near its confluence with the San, in the Sandomierz Basin. It has been part of Świętokrzyskie Voivodeship (Holy ...

Ostrowiec Świętokrzyski Ostrowiec Świętokrzyski (), often referred to as Ostrowiec, is a city in southeastern Poland, in the historical region of Lesser Poland, with 66,258 residents (as of 2021). The town is one of the historic centers of Polish industry and metallurgy ...

and

Iłża Iłża () is a small town in Masovian Voivodeship, Poland. In 2006 Iłża had approximately 5,165 inhabitants. The town belongs to the historical region of Lesser Poland, and from its foundation until 1795, it was part of Lesser Poland’s Sandomie ...

. Because of its rarity and distinctive look, local striped flint is in use today in

jewellery Jewellery (or jewelry in American English) consists of decorative items worn for personal adornment such as brooches, ring (jewellery), rings, necklaces, earrings, pendants, bracelets, and cufflinks. Jewellery may be attached to the body or the ...

and has become a regional export product. Striped flint was mined by

Neolithic The Neolithic or New Stone Age (from Ancient Greek, Greek 'new' and 'stone') is an archaeological period, the final division of the Stone Age in Mesopotamia, Asia, Europe and Africa (c. 10,000 BCE to c. 2,000 BCE). It saw the Neolithic Revo ...

people near Krzemionki Opatowskie village around 4,000 BC, and it was used in manufacturing of axes.

Geology

Upper

Jurassic The Jurassic ( ) is a Geological period, geologic period and System (stratigraphy), stratigraphic system that spanned from the end of the Triassic Period million years ago (Mya) to the beginning of the Cretaceous Period, approximately 143.1 Mya. ...

( Oxfordian) striped flint from Lesser Poland consists mainly of α-

quartz Quartz is a hard, crystalline mineral composed of silica (silicon dioxide). The Atom, atoms are linked in a continuous framework of SiO4 silicon–oxygen Tetrahedral molecular geometry, tetrahedra, with each oxygen being shared between two tet ...

. Morphology of grains indicates that the quartz is not a product of

opal Opal is a hydrated amorphous form of silicon dioxide, silica (SiO2·''n''H2O); its water content may range from 3% to 21% by weight, but is usually between 6% and 10%. Due to the amorphous (chemical) physical structure, it is classified as a ...

and

chalcedony Chalcedony ( or ) is a cryptocrystalline form of silica, composed of very fine intergrowths of quartz and moganite. These are both silica minerals, but they differ in that quartz has a trigonal crystal structure, while moganite is monoclinic ...

conversion, but it precipitated directly from the seawater. The

crystallinity Crystallinity refers to the degree of structural order in a solid. In a crystal, the atoms or molecules are arranged in a regular, periodic manner. The degree of crystallinity has a large influence on hardness, density, transparency and diffusi ...

is higher in the centre of a

concretion A concretion is a hard and compact mass formed by the precipitation of mineral cement within the spaces between particles, and is found in sedimentary rock or soil. Concretions are often ovoid or spherical in shape, although irregular shapes a ...

. Sometimes chalcedony is present, being a product of recrystalization of opal. Other minerals can be found in small quantities:

clay minerals Clay minerals are hydrous aluminium phyllosilicates (e.g. kaolin, Al2 Si2 O5( OH)4), sometimes with variable amounts of iron, magnesium, alkali metals, alkaline earths, and other cations found on or near some planetary surfaces. Clay mineral ...

, iron oxides and hydroxides,

calcite Calcite is a Carbonate minerals, carbonate mineral and the most stable Polymorphism (materials science), polymorph of calcium carbonate (CaCO3). It is a very common mineral, particularly as a component of limestone. Calcite defines hardness 3 on ...

feldspar Feldspar ( ; sometimes spelled felspar) is a group of rock-forming aluminium tectosilicate minerals, also containing other cations such as sodium, calcium, potassium, or barium. The most common members of the feldspar group are the ''plagiocl ...

mica Micas ( ) are a group of silicate minerals whose outstanding physical characteristic is that individual mica crystals can easily be split into fragile elastic plates. This characteristic is described as ''perfect basal cleavage''. Mica is co ...

glauconite Glauconite is an iron potassium phyllosilicate ( mica group) mineral of characteristic green color which is very friable and has very low weathering resistance. It crystallizes with a monoclinic geometry. Its name is derived from the Greek ...

zircon Zircon () is a mineral belonging to the group of nesosilicates and is a source of the metal zirconium. Its chemical name is zirconium(IV) silicate, and its corresponding chemical formula is Zr SiO4. An empirical formula showing some of th ...

tourmaline Tourmaline ( ) is a crystalline silicate mineral, silicate mineral group in which boron is chemical compound, compounded with chemical element, elements such as aluminium, iron, magnesium, sodium, lithium, or potassium. This gemstone comes in a ...

and

rutile Rutile is an oxide mineral composed of titanium dioxide (TiO2), the most common natural form of TiO2. Rarer polymorphs of TiO2 are known, including anatase, akaogiite, and brookite. Rutile has one of the highest refractive indices at vis ...

. Different colouring of individual bands is linked to an increased and decreased number and size of pores that brought about different light reflection. Fewer and smaller pores reflect less light.{{cite book , last1=Król , first1=Paweł , url=http://issuu.com/pawekrol/docs/historia_krzemienia_geologia , title=Rodzaje, występowanie i geneza krzemieni. Zarys Problematyki. Historia krzemienia , last2=Migaszewski , first2=Zdzisław , publisher=Muzeum Narodowe w Kielcach , year=2009 , pages=45 , language=pl , trans-title=Types, localization and genesis of flints. Outline. History of flint

References

Flint (rock) Świętokrzyskie Voivodeship Quartz gemstones